U.S. patent application number 12/826087 was filed with the patent office on 2011-12-29 for flame resistant polyester compositions, method of manufacture, and articles thereof.
This patent application is currently assigned to SABIC Innovative Plastics IP B.V.. Invention is credited to TIANHUA DING, RODNEY FONSECA, SUNG DUG KIM, CHRIS VAN DER WEELE.
Application Number | 20110319534 12/826087 |
Document ID | / |
Family ID | 44539182 |
Filed Date | 2011-12-29 |
![](/patent/app/20110319534/US20110319534A1-20111229-C00001.png)
United States Patent
Application |
20110319534 |
Kind Code |
A1 |
DING; TIANHUA ; et
al. |
December 29, 2011 |
FLAME RESISTANT POLYESTER COMPOSITIONS, METHOD OF MANUFACTURE, AND
ARTICLES THEREOF
Abstract
A thermoplastic polyester composition comprising, based on the
total weight of the composition, a chlorine- and bromine-free
combination of: from 40 to 60 wt % of a modified poly(1,4-butylene
terephthalate); from 25 to 35 wt % of a reinforcing filler; from 2
to 8 wt % of a flame retardant synergist selected from the group
consisting of melamine polyphosphate, melamine cyanurate, melamine
pyrophosphate, melamine phosphate, and combinations thereof; from 5
to 15 wt % of a phosphinate salt flame retardant; from more than 0
to less than 5 wt % of an impact modifier component comprising a
poly(ether-ester) elastomer and a (meth)acrylate impact modifier;
from more than 0 to 5 wt % poly(tetrafluoroethylene) encapsulated
by a styrene-acrylonitrile copolymer; from more than 0 to 2 wt % of
a stabilizer; wherein the thermoplastic polyester composition
contains less than 5 wt % of a polyetherimide.
Inventors: |
DING; TIANHUA; (Newburgh,
IN) ; FONSECA; RODNEY; (NEWBURGH, IN) ; KIM;
SUNG DUG; (San Jose, CA) ; VAN DER WEELE; CHRIS;
(Sommelsdijk, NL) |
Assignee: |
SABIC Innovative Plastics IP
B.V.
Bergen op Zoom
NL
|
Family ID: |
44539182 |
Appl. No.: |
12/826087 |
Filed: |
June 29, 2010 |
Current U.S.
Class: |
524/100 |
Current CPC
Class: |
C08L 33/00 20130101;
C08L 67/02 20130101; C08K 5/5399 20130101; C08L 67/025 20130101;
C08L 2666/02 20130101; C08K 5/34928 20130101; C08K 5/5313 20130101;
C08L 67/02 20130101; C08K 5/34922 20130101 |
Class at
Publication: |
524/100 |
International
Class: |
C08K 5/3492 20060101
C08K005/3492 |
Claims
1. A thermoplastic polyester composition comprising, based on the
total weight of the composition, a chlorine- and bromine-free
combination of: (a) from 40 to 60 wt % of a modified
poly(1,4-butylene terephthalate) that (1) is derived from a
poly(ethylene terephthalate) component selected from the group
consisting of a poly(ethylene terephthalate), a poly(ethylene
terephthalate)copolymer, and a combination thereof, and (2) has at
least one residue derived from the poly(ethylene terephthalate)
component; (b) from 25 to 35 wt % of a reinforcing filler; (c) from
2 to 8 wt % of a flame retardant synergist selected from the group
consisting of melamine polyphosphate, melamine cyanurate, melamine
pyrophosphate, melamine phosphate, and combinations thereof; (d)
from 5 to 15 wt % of a phosphorous flame retardant comprising: a
phosphinate of formula (I)
[(R.sup.1)(R.sup.2)(PO)--O].sup.-.sub.mM.sup.m+ (I), a
diphosphinate of formula (II)
[(O--POR.sup.1)(R.sup.3)(POR.sup.2--O)].sup.2-.sub.nM.sup.m+.sub.x
(II), and/or a polymer derived from the phosphinate of formula (I)
or the diphosphinate of the formula (II), wherein R.sup.1 and
R.sup.2 are each independently the same or different, and are H,
linear or branched C.sub.1-C.sub.6 alkyl, or C.sub.6-C.sub.10 aryl;
R.sup.3 is C.sub.1-C.sub.10, linear or branched alkylene,
C.sub.6-C.sub.10 arylene, C.sub.7-C.sub.11 alkylarylene, or
C.sub.7-C.sub.11 arylalkylene; M is an alkaline earth metal, alkali
metal, Al, Ti, Zn, Fe, or B; m is 1, 2, 3 or 4; n is 1, 2, or 3;
and x is 1 or 2; (e) from more than 0 to less than 5 wt % of an
impact modifier component comprising a poly(ether-ester)elastomer
and a (meth)acrylate impact modifier; (f) from more than 0 to 5 wt
% poly(tetrafluoroethylene) encapsulated by a styrene-acrylonitrile
copolymer; and (g) from more than 0 to 2 wt % of a stabilizer;
wherein the thermoplastic polyester composition contains less than
5 wt % of a polyetherimide.
2. The thermoplastic polyester composition of claim 1, wherein the
poly(ether-ester)elastomer comprises long-chain ester units of
formula (III): -GOC(O)R'C(0)O-- (III); and short-chain ester units
having units of formula (IV): -DOC(O)R'C(0)O-- (IV), wherein R' is
a divalent aromatic radical remaining after removal of carboxyl
groups from terephthalic acid, isophthalic acid, or a combination
of terephthalic acid and isophthalic acid; G is a divalent
polyalkylene oxide radical remaining after removal of terminal
hydroxyl groups from a poly(alkylene oxide) glycol having a
number-average molecular weight of 100 to 2500 Daltons; and D is
the divalent alkylene radical remaining after removal of hydroxyl
groups from an aliphatic diol having a molecular weight from 62 to
286.
3. The thermoplastic polyester composition of claim 1, wherein the
poly(ether-ester)elastomer is a poly(butylene
terephthalate-polytetrahydrofuran) block copolymer.
4. The thermoplastic polyester composition of claim 1, wherein the
(meth)acrylate impact modifier is a core-shell (meth)acrylate
impact modifier having a crosslinked poly(butyl acrylate) core with
a grafted poly(methyl methacrylate) shell.
5. The thermoplastic polyester composition of claim 1, wherein the
phosphorus flame retardant is present in an amount ranging from 11
to 12.5 wt %.
6. The thermoplastic polyester composition of claim 1, wherein the
impact modifier is present in an amount ranging from 2 to 2.5 wt
%
7. The thermoplastic polyester composition of claim 1, wherein the
composition contains no polyetherimide, and an article extruded
from the composition exhibits a CTI (Comparative Tracking Index) of
600 volts.
8. The thermoplastic polyester composition of claim 1, wherein the
flame retardant comprises the phosphinate of formula (I).
9. The thermoplastic polyester composition of claim 1, wherein the
phosphinate of formula (I), the diphosphinate of formula (II),
and/or a polymer thereof is present in an amount from more than 10
to 15 wt %, based on the total weight of the composition.
10. An article comprising the thermoplastic polyester composition
of claim 1.
11. The article of claim 10, wherein the article is selected from
the group consisting of computer fans, electrical connectors,
automotive battery housings, and lighting sockets.
12. A thermoplastic polyester composition comprising, based on the
weight of the composition, a chlorine- and bromine-free combination
of: (a) from 40 to 60 wt % of a modified poly(1,4-butylene
terephthalate) that (1) is derived from a poly(ethylene
terephthalate) component selected from the group consisting of a
poly(ethylene terephthalate), a poly(ethylene
terephthalate)copolymer, and a combination thereof, and (2) has at
least one residue derived from the poly(ethylene terephthalate)
component; (b) from 25 to 35 wt % of a glass fiber filler; (c) from
2 to 8 wt % of a flame retardant synergist selected from the group
consisting of melamine polyphosphate, melamine cyanurate, melamine
pyrophosphate, melamine phosphate, and combinations thereof; (d)
from more than 10 to 15 wt % a phosphinate of formula (I)
[(R.sup.1)(R.sup.2)(PO)--O].sup.-.sub.mM.sup.m+ (I), a
diphosphinate of formula (II)
[(O--POR.sup.1)(R.sup.3)(POR.sup.2--O)].sup.2-.sub.nM.sup.m+.sub.x
(II), and/or a polymer derived from the phosphinate of formula (I)
or the diphosphinate of the formula (II), wherein R.sup.1 and
R.sup.2 are identical or different and are H, linear or branched
C.sub.1-C.sub.6 alkyl, or C.sub.6-C.sub.10 aryl; R.sup.3 is
C.sub.1-C.sub.10, linear or branched alkylene, C.sub.6-C.sub.10
arylene, C.sub.7-C.sub.11 alkylarylene, or C.sub.7-C.sub.11
arylalkylene; M is an alkaline earth metal, alkali metal, Al, Ti,
Zn, Fe, or B; m is 1, 2, 3 or 4; n is 1, 2, or 3; and x is 1 or 2;
(e) at least 1% to less than 5 weight % of impact modifier
component comprising a combination of (i) a poly(ether-ester)
elastomer and (ii) a core-shell (meth)acrylate impact modifier;
wherein the poly(ether-ester)elastomer comprises long-chain ester
units of formula (III): -GOCOR'COO-- (III); and short-chain ester
units having units of formula (IV): -DOCOR'COO-- (IV), wherein R'
is a divalent aromatic radical remaining after removal of carboxyl
groups from terephthalic acid, isophthalic acid, or a combination
of terephthalic acid and isophthalic acid; G is a divalent
polyalkylene oxide radical remaining after removal of terminal
hydroxyl groups from a poly(alkylene oxide) glycol having a
number-average molecular weight of 100 to 2500; and D is a divalent
alkylene radical remaining after removal of hydroxyl groups from
aliphatic diols having a molecular weight from 62 to 286; and
wherein the core-shell meth(acrylate) impact modifier has a
crosslinked poly(butyl acrylate) core with a grafted poly(methyl
methacrylate) shell; (f) from more than 0 to 5 wt %
poly(tetrafluoroethylene) encapsulated by a styrene-acrylonitrile
copolymer; and (g) from more than 0 wt % to 2 wt % of a stabilizer;
wherein the halogen free composition contains less than 5 wt % of a
polyetherimide; and wherein an article molded from the composition
exhibits (a) a flexural modulus that is more than 9800 MPa, (b) a
flexural stress that is more than 150 MPa, (c) an unnotched impact
strength that is more than 470 Joules/meter, and (d) a V0 rating at
0.8 mm, measured in accordance with UL 94.
13. An article comprising the thermoplastic polyester composition
of claim 12.
14. The article of claim 13, wherein the article is selected from
the group consisting of computer fans, electrical connectors,
automotive battery housings, and lighting sockets.
15. A thermoplastic polyester composition comprising, based on the
weight of the composition, a halogen-free combination of: (a) from
40 to 60 wt % of a modified poly(1,4-butylene terephthalate) that
(1) is derived from a poly(ethylene terephthalate) component
selected from the group consisting of a poly(ethylene
terephthalate), a poly(ethylene terephthalate)copolymer, and a
combination thereof, and (2) has at least one residue derived from
the poly(ethylene terephthalate) component; (b) from 25 to 35 wt %
glass fiber filler; (c) from 2 to 8 wt % of a flame retardant
synergist selected from the group consisting of melamine
polyphosphate, melamine cyanurate, melamine pyrophosphate, melamine
phosphate, and combinations thereof; (d) from more than 10 to 15 wt
% a phosphinate of formula (I)
[(R.sup.1)(R.sup.2)(PO)--O].sup.-.sub.mM.sup.m+ (I), a
diphosphinate of formula (II)
[(O--POR.sup.1)(R.sup.3)(POR.sup.2--O)].sup.2-.sub.nM.sup.m+.sub.x
(II), and/or a polymer derived from the phosphinate of formula (I)
or the diphosphinate of the formula (II), wherein R.sup.1 and
R.sup.2 are identical or different and are H, or linear or branched
C.sub.1-C.sub.6 alkyl; R.sup.3 is C.sub.1-C.sub.10, linear or
branched alkylene; M is aluminum; m is 3; n is 3; and x is 1 or 2;
(e) at least 1 to less than 5 wt % of impact modifier component
comprising a combination of (i) a poly(butylene
terephthalate-polytetrahydrofuran) block copolymer and (ii) a
core-shell (meth)acrylate impact modifier having a crosslinked
poly(butyl acrylate) core with a grafted poly(methyl methacrylate)
shell; (f) from more than 0 to 5 wt % poly(tetrafluoroethylene)
encapsulated by a styrene-acrylonitrile copolymer; and (g) from
more than 0 wt % to 2 wt % of a stabilizer; wherein the halogen
free composition contains less than 2 wt % of a polyetherimide; and
wherein an article molded from the composition exhibits (a) a
flexural modulus that is more than 9800 MPa, (b) a flexural stress
is more than 150 MPa, (c) an unnotched impact strength that is more
than 470 Joules/meter, and (d) a V0 rating at 0.8 mm, measured in
accordance with UL 94.
16. An article comprising the composition of claim 15.
17. The article of claim 16, wherein the article is selected from
the group consisting of computer fans, electrical connectors,
automotive battery housings, and lighting sockets.
Description
BACKGROUND
[0001] This disclosure relates to polyester compositions, method of
manufacture of the compositions, and articles thereof.
[0002] Thermoplastic polyester compositions, such as poly(alkylene
terephthalates), have valuable characteristics including strength,
toughness, high gloss, and solvent resistance. Polyesters therefore
have utility as materials for a wide range of applications, from
automotive parts to electric and electronic appliances. Because of
their wide use, particularly in electronic applications, it is
desirable to provide flame retardancy to polyesters.
[0003] Numerous flame retardants (FR) for polyesters are known, but
many contain halogens, usually chlorine and/or bromine. Halogenated
flame retardant agents are less desirable because of the increasing
demand for ecologically friendly ingredients. Halogen-free
flame-retardants, such as phosphorus- and nitrogen-based compounds
can be used as well. Unfortunately, it can be difficult to achieve
excellent flame retardancy in very thin sections.
[0004] More ecologically compatible flame retardant (eco-FR)
formulations based on aluminum salts of phosphinic or diphosphinic
acid compounds and melamine compounds have been developed to
overcome environmental issues of halogenated flame retardants.
However, these eco-FR compositions can have reduced impact strength
and tensile strength, as well as less desirable flow properties
compared to compositions having halogenated flame retardants. The
addition of small amounts of a polyetherimide (PEI), in particular
ULTEM 1010 from Sabic Innovative Plastics, has boosted the
mechanical properties of the eco-FR compositions. However, in some
circumstances PEI lowers the comparative tracking index (CTI)
compared to halogenated frame retardants, i.e., the presence of PEI
can increase the tendency to form conductive leakage paths on the
surface of a molded article.
[0005] Thus, there remains a need for eco-FR thermoplastic
polyester compositions having good flame retardant properties and
comparable or improved mechanical properties, including ductility,
flexural strength, CTI, and stiffness relative to compositions
comprising halogenated flame retardants and eco-FR compositions
comprising PEI.
BRIEF SUMMARY OF THE INVENTION
[0006] Disclosed herein is a thermoplastic polyester composition
comprising, based on the total weight of the composition, a
chlorine- and bromine-free combination of: (a) from 40 to 60 wt %
of a modified poly(1,4-butylene terephthalate) that (1) is derived
from a poly(ethylene terephthalate) component selected from the
group consisting of a poly(ethylene terephthalate), a poly(ethylene
terephthalate)copolymer, and a combination thereof, and (2) has at
least one residue derived from the poly(ethylene terephthalate)
component; (b) from 25 to 35 wt % of a reinforcing filler, (c) from
2 to 8 wt % of a flame retardant synergist selected from the group
consisting of melamine polyphosphate, melamine cyanurate, melamine
pyrophosphate, melamine phosphate, and combinations thereof; (d)
from 5 to 15 wt % of a phosphorous flame retardant comprising: a
phosphinate of formula (I)
[(R.sup.1)(R.sup.2)(PO)--O].sup.-.sub.mM.sup.m+ (I),
a diphosphinate of formula (II)
[(O--POR.sup.1)(R.sup.3)(POR.sup.2--O)].sup.2-.sub.nM.sup.m+.sub.x
(II),
and/or a polymer derived from the phosphinate of formula (I) or the
diphosphinate of the formula (II), wherein R.sup.1 and R.sup.2 are
each independently the same or different, and are H, linear or
branched C.sub.1-C.sub.6 alkyl, or C.sub.6-C.sub.10 aryl; R.sup.3
is C.sub.1-C.sub.10, linear or branched alkylene, C.sub.6-C.sub.10
arylene, C.sub.7-C.sub.11 alkylarylene, or C.sub.7-C.sub.11
arylalkylene; M is an alkaline earth metal, alkali metal, Al, Ti,
Zn, Fe, or B; m is 1, 2, 3 or 4; n is 1, 2, or 3; and x is 1 or 2;
(e) from more than 0 to less than 5 wt % of an impact modifier
component comprising a poly(ether-ester)elastomer and a
(meth)acrylate impact modifier, (f) from more than 0 to 5 wt %
poly(tetrafluoroethylene) encapsulated by a styrene-acrylonitrile
copolymer; (g) from more than 0 to 2 wt % of a stabilizer, wherein
the thermoplastic polyester composition contains less than 5 wt %
of a polyetherimide.
[0007] Also disclosed is a thermoplastic polyester composition
comprising, based on the weight of the composition, a chlorine- and
bromine-free combination of: (a) from 40 to 60 wt % of a modified
poly(1,4-butylene terephthalate) that (1) is derived from a
poly(ethylene terephthalate) component selected from the group
consisting of a poly(ethylene terephthalate), a poly(ethylene
terephthalate)copolymer, and a combination thereof, and (2) has at
least one residue derived from the poly(ethylene terephthalate)
component; (b) from 25 to 35 wt % of a glass fiber filler; (c) from
2 to 8 wt % of a flame retardant synergist selected from the group
consisting of melamine polyphosphate, melamine cyanurate, melamine
pyrophosphate, melamine phosphate, and combinations thereof; (d)
from more than 10 to 15 wt % a phosphinate of formula (I)
[(R.sup.1)(R.sup.2)(PO)--O].sup.-.sub.mM.sup.m+ (I),
[0008] a diphosphinate of formula (II)
[(O--POR.sup.1)(R.sup.3)(POR.sup.2--O)].sup.2-.sub.nM.sup.m+.sub.x
(II),
and/or a polymer derived from the phosphinate of formula (I) or the
diphosphinate of the formula (II), wherein R.sup.1 and R.sup.2 are
identical or different and are H, linear or branched
C.sub.1-C.sub.6 alkyl, or C.sub.6-C.sub.10 aryl; R.sup.3 is
C.sub.1-C.sub.10, linear or branched alkylene, C.sub.6-C.sub.10
arylene, C.sub.7-C.sub.11 alkylarylene, or C.sub.7-C.sub.11
arylalkylene; M is an alkaline earth metal, alkali metal, Al, Ti,
Zn, Fe, or B; m is 1, 2, 3 or 4; n is 1, 2, or 3; and x is 1 or 2;
(e) at least 1% to less than 5 weight % of impact modifier
component comprising a combination of (i) a
poly(ether-ester)elastomer and (ii) a core-shell (meth)acrylate
impact modifier; wherein the poly(ether-ester)elastomer comprises
long-chain ester units of formula (III):
-GOCOR'COO-- (III);
and short-chain ester units having units of formula (IV):
-DOCOR'COO-- (IV),
wherein R' is a divalent aromatic radical remaining after removal
of carboxyl groups from terephthalic acid, isophthalic acid, or a
combination of terephthalic acid and isophthalic acid; G is a
divalent polyalkylene oxide radical remaining after removal of
terminal hydroxyl groups from a poly(alkylene oxide)glycol having a
number-average molecular weight of 100 to 2500; and D is a divalent
alkylene radical remaining after removal of hydroxyl groups from
aliphatic diols having a molecular weight from 62 to 286; and
wherein the core-shell meth(acrylate) impact modifier has a
crosslinked poly(butyl acrylate) core with a grafted poly(methyl
methacrylate) shell; (f) from more than 0 to 5 wt %
poly(tetrafluoroethylene) encapsulated by a styrene-acrylonitrile
copolymer; and (g) from more than 0 wt % to 2 wt % of a stabilizer;
wherein the halogen free composition contains less than 5 wt % of a
polyetherimide; and wherein an article molded from the composition
exhibits (a) a flexural modulus that is more than 9800 MPa, (b) a
flexural stress that is more than 150 MPa, (c) an unnotched impact
strength that is more than 470 Joules/meter, and (d) a V0 rating at
0.8 mm, measured in accordance with UL 94.
[0009] Still further disclosed is a thermoplastic polyester
composition comprising, based on the weight of the composition, a
halogen-free combination of: (a) from 40 to 60 wt % of a modified
poly(1,4-butylene terephthalate) that (1) is derived from a
poly(ethylene terephthalate) component selected from the group
consisting of a poly(ethylene terephthalate), a poly(ethylene
terephthalate)copolymer, and a combination thereof, and (2) has at
least one residue derived from the poly(ethylene terephthalate)
component; (b) from 25 to 35 wt % glass fiber filler; (c) from 2 to
8 wt % of a flame retardant synergist selected from the group
consisting of melamine polyphosphate, melamine cyanurate, melamine
pyrophosphate, melamine phosphate, and combinations thereof; (d)
from more than 10 to 15 wt % a phosphinate of formula (I)
[(R.sup.1)(R.sup.2)(PO)--O].sup.-.sub.mM.sup.m+ (I),
a diphosphinate of formula (II)
[(O--POR.sup.1)(R.sup.3)(POR.sup.2--O)].sup.2-.sub.nM.sup.m+.sub.x
(II),
and/or a polymer derived from the phosphinate of formula (I) or the
diphosphinate of the formula (II), wherein R.sup.1 and R.sup.2 are
identical or different and are H, or linear or branched
C.sub.1-C.sub.6 alkyl; R.sup.3 is C.sub.1-C.sub.10, linear or
branched alkylene; M is aluminum; m is 3; n is 3; and x is 1 or 2;
(e) at least 1 to less than 5 wt % of impact modifier component
comprising a combination of (i) a poly(butylene
terephthalate-polytetrahydrofuran) block copolymer and (ii) a
core-shell (meth)acrylate impact modifier having a crosslinked
poly(butyl acrylate) core with a grafted poly(methyl methacrylate)
shell; (f) from more than 0 to 5 wt % poly(tetrafluoroethylene)
encapsulated by a styrene-acrylonitrile copolymer; and (g) from
more than 0 wt % to 2 wt % of a stabilizer; wherein the halogen
free composition contains less than 2 wt % of a polyetherimide; and
wherein an article molded from the composition exhibits (a) a
flexural modulus that is more than 9800 MPa, (b) a flexural stress
is more than 150 MPa, (c) an unnotched impact strength that is more
than 470 Joules/meter, and (d) a V0 rating at 0.8 mm, measured in
accordance with UL 94.
[0010] Also disclosed are methods for the manufacture of the
foregoing compositions.
[0011] Still further disclosed are articles comprising the
foregoing compositions.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Our invention is based on the discovery that that it is
possible to make a glass filled, halogen free flame retarding
composition that exhibits many useful properties: namely, good
flame retardancy performance (i.e., V0 at 0.80 mm), higher CTI
performance, improved impact properties and improved flexural
properties by the use of a specific combination of elastomers, as
compared to a composition that does not use the combination of
elastomers.
[0013] Described herein is a flame retardant thermoplastic
polyester composition that is chlorine- and bromine-free, and that
includes a polyester, a reinforcing filler, a melamine-based flame
retardant synergist, a phosphinate salt flame retardant, an
anti-drip agent, an impact modifier component comprising a
poly(ether-ester)elastomer and an acrylate impact modifier, a
stabilizer, and only optionally a polyetherimide. Use of the
specific components in the amounts disclosed herein allows
manufacture of a chlorine- and bromine-free composition with
excellent flame retardance and improved flow and CTI, while
maintaining and the desirable mechanical properties of currently
used glass-filled eco-FR formulations, even in the absence of a
polyetherimide. In particular, the compositions can have very
useful impact strength properties, flexural properties, heat
stability, flow properties, and/or high resistance against
electrical breakdown.
[0014] As used herein the singular forms "a," "an," and "the"
include plural referents. The term "combination" is inclusive of
blends, mixtures, alloys, reaction products, and the like. Unless
defined otherwise, technical and scientific terms used herein have
the same meaning as is commonly understood by one of skill.
Compounds are described using standard nomenclature. The term "and
a combination thereof" is inclusive of the named component and/or
other components not specifically named that have essentially the
same function.
[0015] Other than in the operating examples or where otherwise
indicated, all numbers or expressions referring to quantities of
ingredients, reaction conditions, and the like, used in the
specification and claims are to be understood as modified in all
instances by the term "about." Various numerical ranges are
disclosed in this patent application. Because these ranges are
continuous, they include every value between the minimum and
maximum values. The endpoints of all ranges reciting the same
characteristic or component are independently combinable and
inclusive of the recited endpoint. Unless expressly indicated
otherwise, the various numerical ranges specified in this
application are approximations. The term "from more than 0 to" an
amount means that the named component is present in some amount
more than 0, and up to and including the higher named amount.
[0016] All ASTM tests and data are from the 2003 edition of the
Annual Book of ASTM Standards unless otherwise indicated. All cited
references are incorporated herein by reference.
[0017] For the sake of clarity, the terms "terephthalic acid
group," "isophthalic acid group," "butanediol group," and "ethylene
glycol group" have the following meanings. The term "terephthalic
acid group" in a composition refers to a divalent 1,4-benzene
radical (-1,4-(C.sub.6H.sub.4)--) remaining after removal of the
carboxylic groups from terephthalic acid-. The term "isophthalic
acid group" refers to a divalent 1,3-benzene radical
(-(-1,3-C.sub.6H.sub.4)--) remaining after removal of the
carboxylic groups from isophthalic acid. The "butanediol group"
refers to a divalent butylene radical (--(C.sub.4H.sub.8)--)
remaining after removal of hydroxyl groups from butanediol. The
term "ethylene glycol group" refers to a divalent ethylene radical
(--(C.sub.2H.sub.4)--) remaining after removal of hydroxyl groups
from ethylene glycol. With respect to the terms "terephthalic acid
group," "isophthalic acid group," "ethylene glycol group," "butane
diol group," and "diethylene glycol group" being used in other
contexts, e.g., to indicate the weight % of the group in a
composition, the term "isophthalic acid group(s)" means the group
having the formula (--O(CO)C.sub.6H.sub.4(CO)--), the term
"terephthalic acid group" means the group having the formula
(--O(CO)C.sub.6H.sub.4(CO)--), the term diethylene glycol group
means the group having the formula
(--O(C.sub.2H.sub.4)O(C.sub.2H.sub.4)--), the term "butanediol
group" means the group having the formula (--O(C.sub.4H.sub.8)--),
and the term "ethylene glycol groups" means the group having
formula (--O(C.sub.2H.sub.4)--).
[0018] Polyesters for use in the present thermoplastic compositions
having repeating structural units of formula (I)
##STR00001##
wherein each T is independently the same or different divalent
C.sub.6-10 aromatic group derived from a dicarboxylic acid or a
chemical equivalent thereof, and each D is independently a divalent
C.sub.2-4 alkylene group derived from a dihydroxy compound or a
chemical equivalent thereof. Copolyesters containing a combination
of different T and/or D groups can be used. Chemical equivalents of
diacids include the corresponding esters, alkyl esters, e.g.,
C.sub.1-3 dialkyl esters, diaryl esters, anhydrides, salts, acid
chlorides, acid bromides, and the like. Chemical equivalents of
dihydroxy compounds include the corresponding esters, such as
C.sub.1-3 dialkyl esters, diaryl esters, and the like. The
polyesters can be branched or linear.
[0019] Exemplary polyesters include poly(alkylene terephthalate)
("PAT"), poly(1,4-butylene terephthalate), ("PBT"), poly(ethylene
terephthalate) ("PET"), poly(ethylene naphthalate) ("PEN"),
poly(butylene naphthalate), ("PBN"), poly(propylene terephthalate)
("PPT"), poly(cyclohexane dimethanol terephthalate) ("PCT"),
poly(cyclohexane-1,4-dimethylene cyclohexane-1,4-dicarboxylate)
also known as poly(1,4-cyclohexanedimethanol 1,4-dicarboxylate)
("PCCD"), poly(cyclohexanedimethanol terephthalate),
poly(cyclohexylenedimethylene-co-ethylene terephthalate),
cyclohexanedimethanol-terephthalic acid-isophthalic acid copolymers
and cyclohexanedimethanol-terephthalic acid-ethylene glycol ("PCTG"
or "PETG") copolymers. When the molar proportion of
cyclohexanedimethanol is higher than that of ethylene glycol the
polyester is termed PCTG. When the molar proportion of ethylene
glycol is higher than that of cyclohexane dimethanol the polyester
is termed PETG.
[0020] The polyesters can be obtained by methods well known to
those skilled in the art, including, for example, interfacial
polymerization, melt-process condensation, solution phase
condensation, and transesterification polymerization. Such
polyester resins are typically obtained through the condensation or
ester interchange polymerization of the diol or diol equivalent
component with the diacid or diacid chemical equivalent component.
Methods for making polyesters and the use of polyesters in
thermoplastic molding compositions are known in the art.
Conventional polycondensation procedures are described in the
following, see, generally, U.S. Pat. Nos. 2,465,319, 5,367,011 and
5,411,999. The condensation reaction can be facilitated by the use
of a catalyst, with the choice of catalyst being determined by the
nature of the reactants. The various catalysts are known in the
art. For example, a dialkyl ester such as dimethyl terephthalate
can be transesterified with butylene glycol using acid catalysis,
to generate poly(butylene terephthalate). It is possible to use a
branched polyester in which a branching agent, for example, a
glycol having three or more hydroxyl groups or a trifunctional or
multifunctional carboxylic acid has been incorporated.
[0021] The polyester component can comprise a modified
poly(butylene terephthalate), that is, a PBT derived from
poly(ethylene terephthalate), for example waste PET such as soft
drink bottles. The PET-derived PBT (referred to herein for
convenience as "modified PBT") (1) can be derived from a
poly(ethylene terephthalate) component selected from the group
consisting of poly(ethylene terephthalate), poly(ethylene
terephthalate) copolymers, and a combination thereof, and (2) has
at least one residue derived from the poly(ethylene terephthalate)
component. The modified PBT can further be derived from a
biomass-derived 1,4-butanediol, e.g., corn derived 1,4-butanediol
or a 1,4-butanediol derived from a cellulosic material. Unlike
conventional molding compositions containing virgin PBT (PBT that
is derived from monomers), the modified PBT contains a
poly(ethylene terephthalate) residue, e.g., a material such as
ethylene glycol and isophthalic acid groups (components that are
not present in virgin, monomer-based PBT). Use of modified PBT can
provide a valuable way to effectively use underutilized scrap PET
(from post-consumer or post-industrial streams) in PBT
thermoplastic molding compositions, thereby conserving
non-renewable resources and reducing the formation of greenhouse
gases, e.g., CO.sub.2.
[0022] The residue derived from the poly(ethylene terephthalate)
component and which is present in the modified PBT can be selected
from the group consisting of ethylene glycol groups, diethylene
glycol groups, isophthalic acid groups, antimony-containing
compounds, germanium-containing compounds, titanium-containing
compounds, cobalt-containing compounds, tin-containing compounds,
aluminum, aluminum salts, 1,3-cyclohexane dimethanol isomers,
1,4-cyclohexane dimethanol isomers, the cis isomer of
1,3-cyclohexane dimethanol, the cis isomer of 1,4-cyclohexane
dimethanol, the trans isomer of 1,3-cyclohexane dimethanol, the
trans isomer of 1,4-cyclohexane dimethanol, alkali salts, alkaline
earth metal salts, including calcium, magnesium, sodium and
potassium salts, phosphorous-containing compounds and anions,
sulfur-containing compounds and anions, naphthalene dicarboxylic
acids, 1,3-propanediol groups, and combinations thereof.
[0023] Depending on factors such as the type and relative amounts
of poly(ethylene terephthalate) and poly(ethylene
terephthalate)copolymers, the residue can include various
combinations. For example, the residue can include mixtures of
ethylene glycol groups and diethylene glycol groups. The residue
can also include mixtures of ethylene glycol groups, diethylene
glycol groups, and isophthalic acid groups. The residue derived
from poly(ethylene terephthalate) can include the cis isomer of
1,3-cyclohexane dimethanol groups, the cis isomer of
1,4-cyclohexane dimethanol groups, the trans isomer of
1,3-cyclohexane dimethanol groups, the trans isomer of
1,4-cyclohexane dimethanol groups, or combinations thereof. The
residue can also be a mixture of ethylene glycol groups, diethylene
glycol groups, isophthalic acid groups, cis isomer of cyclohexane
dimethanol groups, trans isomer of cyclohexane dimethanol groups,
or combinations thereof. The residue derived from poly(ethylene
terephthalate) can also include mixtures of ethylene glycol groups,
diethylene glycol groups, and cobalt-containing compounds. Such
cobalt-containing compound mixture can also contain isophthalic
acid groups.
[0024] The amount of the ethylene glycol groups, diethylene glycol
groups, and isophthalic groups in the polymeric backbone of the
modified PBT component can vary. The modified PBT ordinarily
contains isophthalic acid groups in an amount that is at least 0.1
mole % and can range from 0 or 0.1 to 10 mole % (0 or 0.07 to 7
weight percent (wt %)). The modified PBT component ordinarily
contains ethylene glycol in an amount that is at least 0.1 mole %
and can range from 0.1 to 10 mole % (0.02 to 2 wt %). In an
embodiment, the modified PBT component has an ethylene glycol
content that is more than 0.85 wt %. In another embodiment,
compositions can contain ethylene glycol in an amount from 0.1 to 2
wt %. The modified PBT component can also contain diethylene glycol
in an amount from 0.1 to 10 mole % (0.04 to 4 wt %). The amount of
the butanediol groups is generally about 98 mole % and can vary
from 95 to 99.8 mole % in some embodiments. The amount of the
terephthalic acid groups is generally about 98 mole % and can vary
from 90 to 99.9 mole % in some embodiments. Unless otherwise
specified, all molar amounts of the isophthalic acid groups and/or
terephthalic acid groups are based on the total moles of
diacids/diesters in the composition. Unless otherwise specified,
all molar amounts of the butanediol, ethylene glycol, and
diethylene glycol groups are based on the total moles of diol in
the composition. These weight percent measurements are based on the
above definitions of terephthalic acid groups, isophthalic acid
groups, ethylene glycol groups, and diethylene glycol groups.
[0025] The total amount of the poly(ethylene terephthalate)
component residue in the modified PBT can vary in amounts from 1.8
to 2.5 wt %, or from 0.5 to 2 wt %, or from 1 to 4 wt %, based on
the total weight of the modified PBT. The ethylene glycol,
diethylene glycol, and cyclohexane dimethanol groups can be
present, individually or in combination, in an amount from 0.1 to
10 mole %, based on 100 mole % of glycol in the molding
composition. The isophthalic acid groups can be present in an
amount from 0.1 to 10 mole %, based on 100 mole % of diacid/diester
in the molding composition.
[0026] It has been discovered that when it is desirable to make a
poly(butylene terephthalate)copolymer having a melting temperature
T.sub.m that is at least 200.degree. C., the total amount of
diethylene glycol, ethylene glycol, and isophthalic acid groups
should be within a certain range. As such, the total amount of the
diethylene glycol, ethylene glycol, and isophthalic acid groups in
the modified poly(butylene terephthalate) component can be more
than 0 and less than or equal to 23 equivalents, relative to the
total of 100 equivalents of diol and 100 equivalents of diacid
groups in the modified PBT. The total amount of the isophthalic
acid groups, ethylene glycol groups, and diethylene glycol groups
can be from 3 to less than or equal to 23 equivalents, relative to
the total of 100 equivalents of diol and 100 equivalents of diacid
groups in the PET-derived PBT. Alternatively, the total amount of
the isophthalic acid groups, ethylene glycol groups, and diethylene
glycol groups can be from 3 to less than or equal to 10
equivalents, relative to the total of 100 equivalents of diol and
100 equivalents of diacid groups in the modified PBT. Still
further, the total amount of the isophthalic acid groups, ethylene
glycol groups, and diethylene glycol groups can be from 10 to less
than or equal to 23 equivalents, relative to the total of 100
equivalents of diol and 100 equivalents of diacid groups in the
modified PBT. The diethylene glycol, ethylene glycol, and/or
isophthalic acid can be added during the process.
[0027] The total ethylene glycol groups, isophthalic acid groups,
and diethylene glycol groups can vary, depending on the application
needs. The composition can have total monomer content selected from
the group consisting of ethylene glycol, isophthalic acid groups,
and diethylene glycol groups in an amount from more than 0 and less
than or equal to 17 equivalents relative to the total of 100
equivalents of diol and 100 equivalents of diacid groups in the
modified PBT. Advantageously, such compositions can maintain useful
properties, such as heat deflection temperatures that are more than
80.degree. C.
[0028] It has also been discovered that the total amount of
inorganic residues derived from the poly(ethylene terephthalate)
can be present from more than 0 ppm and up to 1000 ppm. Examples of
such inorganic residues include those selected from the group
consisting of antimony-containing compounds, germanium-containing
compounds, titanium-containing compounds, cobalt-containing
compounds, tin containing compounds, aluminum, aluminum salts,
alkaline earth metal salts, alkali salts, including calcium,
magnesium, sodium and potassium salts, phosphorous-containing
compounds and anions, sulfur-containing compounds and anions, and
combinations thereof. The amounts of inorganic residues can be from
250 to 1000 ppm, and more specifically from 500 to 1000 ppm.
[0029] The PET component from which the modified PBT is made can
have a variety of forms. Generally, the PET component includes
recycle (scrap) PET in flake, powder/chip, film, or pellet form.
Before use, the PET is generally processed to remove impurities
such as paper, adhesives, polyolefin, e.g., polypropylene,
polyvinyl chloride (PVC), nylon, polylactic acid, and other
contaminants. Also, the PET component can include PET that is not
waste in flake, chip, or pellet form. As such, PET that would
ordinarily be deposited in landfills can now be used productively
and effectively. The PET component can also include other
polyesters and/or polyester copolymers. Examples of such materials
include poly(alkylene terephthalates) selected from the group
consisting of poly(ethylene terephthalate), poly(cyclohexane
dimethanol terephthalate), copolyesters of terephthalate esters
with comonomers containing cyclohexanedimethanol and ethylene
glycol, copolyesters of terephthalic acid with comonomers
containing cyclohexane dimethanol and ethylene glycol,
poly(butylene terephthalate), poly(xylylene terephthalate),
poly(butylene terephthalate), poly(trimethylene terephthalate),
polyester naphthalates, and combinations thereof.
[0030] Commercial examples of a modified PBT include those
available under the trade name VALOX iQ PBT, manufactured by SABIC
Innovative Plastics Company. The modified PBT can be derived from
the poly(ethylene terephthalate) component by any method that
involves depolymerization of the poly(ethylene terephthalate)
component and polymerization of the depolymerized poly(ethylene
terephthalate) component with 1,4-butanediol to provide the
modified PBT. For example, the modified poly(butylene
terephthalate) component can be made by a process that involves
depolymerizing a poly(ethylene terephthalate) component selected
from the group consisting of poly(ethylene terephthalate) and
poly(ethylene terephthalate)copolymers, with a 1,4-butanediol
component at a temperature from 180.degree. C. to 230.degree. C.,
under agitation, at a pressure that is at least atmospheric
pressure in the presence of a catalyst component, at an elevated
temperature, under an inert atmosphere, to produce a molten mixture
containing a component selected from the group consisting of
oligomers containing ethylene terephthalate moieties, oligomers
containing ethylene isophthalate moieties, oligomers containing
diethylene terephthalate moieties, oligomers containing diethylene
isophthalate moieties, oligomers containing butylene terephthalate
moieties, oligomers containing butylene isophthalate moieties,
covalently bonded oligomeric moieties containing at least two of
the foregoing moieties, 1,4-butanediol, ethylene glycol, and
combinations thereof; and agitating the molten mixture at
sub-atmospheric pressure and increasing the temperature of the
molten mixture to an elevated temperature under conditions
sufficient to form a modified PBT containing at least one residue
derived from the poly(ethylene terephthalate) component.
[0031] Polyester moieties and the 1,4-butanediol are combined in
the liquid phase under agitation and the 1,4-butanediol can be
continuously refluxed back into the reactor during step (a). The
tetrahydrofuran (THF) and water formed in the stage can be removed
by distillation or partial condensation.
[0032] The poly(ethylene terephthalate) component and the
1,4-butanediol component are generally combined under atmospheric
pressure. In another embodiment, however, it is possible to use
pressures that are higher than atmospheric pressures. For instance,
in an embodiment, the pressure at which the poly(ethylene
terephthalate) component and the 1,4-butanediol are subjected to is
2 atmospheres or higher. For higher pressures, the reaction
mixtures can be depolymerized at temperatures higher than
230.degree. C.
[0033] The temperature at which the poly(ethylene terephthalate)
component and the 1,4-butanediol component are combined and reacted
is sufficient to promote depolymerization of the poly(ethylene
terephthalate) component into a mixture of oligomers containing
ethylene terephthalate moieties, oligomers containing ethylene
isophthalate moieties, oligomers containing diethylene
terephthalate moieties, oligomers containing diethylene
isophthalate moieties, oligomers containing butylene terephthalate
moieties, oligomers containing butylene isophthalate moieties,
covalently bonded oligomeric moieties containing at least two of
the foregoing moieties, 1,4-butanediol, ethylene glycol, and
combinations thereof. The temperature at which the poly(ethylene
terephthalate) component and the 1,4-butanediol component are
combined generally ranges from 180 to 230.degree. C. 1,4-Butanediol
is generally used in excess amount relative to the poly(ethylene
terephthalate) component. In an embodiment, 1,4-butanediol is used
in a molar excess amount from 2 to 20.
[0034] During the initial stage of the process when the
poly(ethylene terephthalate) component and the 1,4-butanediol are
combined and react ("step (a)"), the poly(ethylene terephthalate)
component and the 1,4-butanediol depolymerize into a molten mixture
at a pressure that is at least atmospheric pressure suitable
conditions. 1,4-Butanediol and ethylene glycol are generally
recirculated, and tetrahydrofuran is distilled during "step (a)" of
the process. The molten mixture contains oligomers containing
ethylene terephthalate moieties, oligomers containing ethylene
isophthalate moieties, oligomers containing diethylene
terephthalate moieties, oligomers containing diethylene
isophthalate moieties, oligomers containing butylene terephthalate
moieties, oligomers containing butylene isophthalate moieties,
covalently bonded oligomeric moieties containing at least two of
the foregoing moieties, 1,4-butanediol, ethylene glycol, and
combinations thereof.
[0035] The duration of the step in which poly(ethylene
terephthalate) component reacts with 1,4-butanediol can vary,
depending on factors, such as available equipment, production
needs, desired final properties, and the like. In an embodiment,
this step is carried out in at least 2 hours. In another
embodiment, the step is carried out from 2 to 5 hours.
[0036] The process further includes the step of subjecting the
molten mixture to sub-atmospheric pressure and increasing the
temperature of the molten mixture to a temperature from 240 to
260.degree. C., and thereby forming the modified poly(butylene
terephthalate) component derived from the poly(ethylene
terephthalate) component.
[0037] Excess butanediol, ethylene glycol, and THF are preferably
removed and step (b) is carried out under agitation. The molten
mixture, when placed in sub-atmospheric pressure conditions at a
suitable temperature for a sufficiently long time period,
polymerizes into a modified poly(butylene terephthalate) component
derived from the poly(ethylene terephthalate) component copolymer.
Generally, the molten mixture pressure is subjected to a pressure
from sub-atmospheric to less than 1 Ton (0.133 MPa). In an
embodiment, the pressure is reduced to a pressure from 100 to 0.05
Torr (13.3 to 0.0066 MPa) in a continuous manner. In another
embodiment, the pressure is reduced to a pressure from 10 to 0.1
Ton (1.33 to 0.0133 MPa) in a continuous fashion. Advantageously,
the molten mixture can be placed under sub-atmospheric conditions
without isolation and dissolution of any material from the molten
mixture. The avoidance of this step greatly enhances the utility of
the process.
[0038] During the step when the molten mixture is placed under
sub-atmospheric conditions and the temperature is increased, excess
butanediol, ethylene glycol, and THF are removed from the reactor
and oligomers are allowed to build in molecular weight. Agitation
can be continuously provided to facilitate the removal of the low
boiling components and allow the molecular weight buildup of the
polymer. After sufficient molecular weight is obtained, the
resulting molten PBT polymer is cast from the reactor through a
diehead, cooled with water, stranded and chopped into pellets.
[0039] The duration of the step (step (b) discussed above) in which
the molten mixture polymerizes from poly(ethylene terephthalate)
and poly(butylene terephthalate)oligomers, 1,4-butanediol, and
ethylene glycol can vary, depending on factors, such as equipment
available, production needs, desired final properties, and the
like. In an embodiment, this step is carried out in at least two
hours. In another embodiment, the step is carried out from 2 to 5
hours.
[0040] The temperature at which the molten mixture is placed under
sub-atmospheric conditions is sufficiently high to promote
polymerization of the poly(ethylene terephthalate) and
poly(butylene terephthalate)oligomers, 1,4-butanediol, and ethylene
glycol to the modified poly(butylene terephthalate) component
derived from the poly(ethylene terephthalate) component. Generally,
the temperature is at least 230.degree. C. In an embodiment, the
temperature is from 250.degree. C. to 275.degree. C.
[0041] Both steps of the process can be carried out in the same
reactor. In an embodiment, however, the process is carried out in
two separate reactors, where step (a) is carried out in a first
reactor and when the molten mixture has formed, the molten mixture
is placed in a second reactor and step (b) is carried out. In
another embodiment, the process can be carried out in more than two
reactors. In another embodiment, the process can be carried out in
a continuous series of reactors.
[0042] The catalyst component that facilitates the reaction can be
selected from antimony compounds, tin compounds, titanium
compounds, combinations thereof as well as many other metal
catalysts and combinations of metal catalysts that have been
disclosed in the literature. The amount of the catalyst will vary
depending on the specific need at hand. Suitable amounts of the
catalyst range from 1 to 5000 ppm, or more. The catalyst component
is generally added during the step when the poly(ethylene
terephthalate) component initially combines with the 1,4-butanediol
component. In another embodiment, however, the catalyst component
can be added to the molten mixture that forms after the
poly(ethylene terephthalate) component and the 1,4-butanediol
component are combined.
[0043] The process for making the modified PBT is preferably
carried out under agitative conditions. The term "agitative
conditions" or "agitation" refers to subjecting the poly(ethylene
terephthalate) component and the 1,4-butanediol or the molten
mixture to conditions that involve physically mixing the
poly(ethylene terephthalate) component 1,4-butanediol or molten
mixture under conditions that promote the depolymerization of the
PET when the agitative conditions are applied to poly(ethylene
terephthalate) component 1,4-butanediol, i.e., step (a), or the
polymerization of the PBT from poly(ethylene terephthalate)
oligomers, 1,4-butanediol, and ethylene glycol, i.e., step (b). The
physical mixing can be accomplished by any suitable way. In an
embodiment, a mixer containing rotating shaft and blades that are
perpendicular to the shaft can be used.
[0044] In another embodiment, a process involves the steps of: (a)
reacting (i) a poly(ethylene terephthalate) component selected from
the group consisting of poly(ethylene terephthalate) and
poly(ethylene terephthalate)copolymers with a diol component
selected from the group consisting of ethylene glycol, propylene
glycol, and combinations thereof, in a reactor at a pressure that
is at least atmospheric pressure in the presence of a catalyst
component at a temperature from 190.degree. C. to 250.degree. C.,
under an inert atmosphere, under conditions sufficient to
depolymerize the poly(ethylene terephthalate) component into a
first molten mixture containing components selected from the group
consisting of oligomers containing ethylene terephthalate moieties,
oligomers containing ethylene isophthalate moieties, oligomers
containing diethylene terephthalate moieties, oligomers containing
diethylene isophthalate moieties, oligomers containing trimethylene
terephthalate moieties, oligomers containing trimethylene
isophthalate moieties, covalently bonded oligomeric moieties
containing at least two of the foregoing moieties, ethylene glycol,
propylene glycol and combinations thereof; wherein the
poly(ethylene terephthalate) component and the diol component are
combined under agitation; (b) adding 1,4-butanediol to the first
molten mixture in a reactor in the presence of a catalyst component
at a temperature from 190 to 240.degree. C., under conditions that
are sufficient to form a second molten mixture containing a
component selected from the group consisting of oligomers
containing ethylene terephthalate moieties, oligomers containing
ethylene isophthalate moieties, oligomers containing diethylene
terephthalate moieties, oligomers containing diethylene
isophthalate moieties, oligomers containing trimethylene
terephthalate moieties, oligomers containing trimethylene
isophthalate moieties, oligomers containing butylene terephthalate
moieties, oligomers containing butylene isophthalate moieties,
covalently bonded oligomeric moieties containing at least two of
the foregoing moieties, 1,4-butanediol, propylene glycol, ethylene
glycol, and combinations thereof; and (c) increasing the
temperature of the second molten mixture under sub-atmospheric
conditions and agitation to a temperature from 240 to 260.degree.
C., thereby forming a modified PBT containing at least one residue
derived from the poly(ethylene terephthalate) component.
[0045] This three-step embodiment provides an additional
advantageous way for producing modified PBT copolymers from PET.
The diol component used in step (a) of the three-step embodiment
can be selected from ethylene glycol, propylene glycol, and
combinations thereof. The diol component can be present in step (a)
at a molar amount that is at least half the amount of the ethylene
glycol moieties present in the poly(ethylene terephthalate)
component. The depolymerization of the poly(ethylene terephthalate)
component can be carried out for various times. In an embodiment,
the depolymerization is carried out for at least 25 minutes. The
1,4-butanediol used during step (b) of the three step embodiment
can be added at a molar amount that is in excess relative to the
molar amount of butanediol moieties incorporated into the modified
PBT component obtained in step (c). During the process the
compounds used in the process can be reused and/or collected. In an
embodiment, the diol component selected from the group consisting
of ethylene glycol, propylene glycol, and combinations thereof and
(2) 1,4-butanediol are removed and collected in a vessel in step
(b). In another embodiment, in step (b), 1,4-butanediol is refluxed
back into the reactor and a component selected from the group of
excess butanediol, ethylene glycol, propylene glycol,
tetrahydrofuran, and combinations thereof is removed. Step (b) is
practiced for a sufficient period of time to reduce at least 65% of
ethylene glycol from the second molten mixture. The duration of
step (b) can also vary. In an embodiment, step (b) lasts at least
45 minutes. The pressure at which step (b) is carried out can vary.
In an embodiment, step (b) is carried out in atmospheric
conditions. In another embodiment, step (b) is carried out in
sub-atmospheric conditions. Different combinations are possible. In
an embodiment, step (b) is carried out with excess 1,4-butanediol
and at a pressure from 300 to 1500 mbar absolute (30 to 150 MPa).
In another embodiment, 1,4-butanediol is used in a molar excess
amount from 1.1 to 5. Step (c) of the three-step embodiment can
also be carried out with modifications, depending on the
application. In an embodiment, for example, a component selected
from the group of excess butanediol, ethylene glycol, propylene
glycol, tetrahydrofuran, and combinations thereof is removed during
step (c). The pressure at which step (c) is carried out can also
vary. In an embodiment, step (c) is carried out at a pressure that
is less than 10 mbar (1 MPa). The three-step process can be carried
out in the same reactor. Alternatively, the three-step process can
be carried out in at least two reactors.
[0046] In another embodiment, the three-step process can include
the step of adding a basic compound during step (a), step (b), step
(c), and combinations thereof, and thereby further reduce THF
production. The basic compound, as in the two-step embodiment, can
contain those compounds mentioned above. Alternatively,
difunctional epoxy compounds can be added during step (b) in the
amounts indicated above.
[0047] The process for making the modified PBT copolymer can
contain an additional step in which the PBT formed from the molten
mixture is subjected to solid-state polymerization. Solid-state
polymerization generally involves subjecting the PBT formed from
the molten mixture to an inert atmosphere or sub-atmospheric
pressure and heating to a temperature for a sufficient period of
time to build the molecular weight of the PBT. Generally, the
temperature to which the PBT is heated is below the melting
temperature of the PBT, e.g., from 5.degree. C. to 60.degree. C.
below the melting temperature of the PBT. In an embodiment, such a
temperature can range from 150.degree. C. to 210.degree. C.
Suitable periods of time during which the solid-state
polymerization occurs can range from 2 to 20 hours, depending on
the conditions and equipment. The solid-state polymerization is
generally carried out under tumultuous conditions sufficient to
promote further polymerization of the PBT to a suitable molecular
weight. Such tumultuous conditions can be created by subjecting the
PBT to tumbling, the pumping of inert gas into the system to
promote fluidization of polymer particle, e.g., pellets, chips,
flakes, powder, and the like. The solid-state polymerization can be
carried out at atmospheric pressure and/or under reduced pressure,
e.g. from 1 atmosphere to 1 mbar (101 to 0.1 MPa).
[0048] A combination of polyesters can be used, for example a
combination of virgin polyesters (polyesters derived from monomers
rather than recycled polymer, including virgin poly(1,4-butylene
terephthalate) and modified PBT. Also contemplated herein are
second polyesters comprising minor amounts, e.g., 0.5 to 30 wt %,
of units derived from aliphatic acids and/or aliphatic polyols to
form copolyesters. The aliphatic polyols include glycols, such as
poly(ethylene glycol). Such polyesters can be made following the
teachings of, for example, U.S. Pat. No. 2,465,319 to Whinfield et
al., and U.S. Pat. No. 3,047,539 to Pengilly. Second polyesters
comprising block copolyester resin components are also
contemplated, and can be prepared by the transesterification of (a)
straight or branched chain poly(alkylene terephthalate) and (b) a
copolyester of a linear aliphatic dicarboxylic acid and,
optionally, an aromatic dibasic acid such as terephthalic or
isophthalic acid with one or more straight or branched chain
dihydric aliphatic glycols. Especially useful when high melt
strength is important are branched high melt viscosity resins,
which include a small amount of, e.g., up to 5 mole percent based
on the acid units of a branching component containing at least
three ester forming groups. The branching component can be one that
provides branching in the acid unit portion of the polyester, in
the glycol unit portion, or it can be a hybrid branching agent that
includes both acid and alcohol functionality. Illustrative of such
branching components are tricarboxylic acids, such as trimesic
acid, and lower alkyl esters thereof, and the like; tetracarboxylic
acids, such as pyromellitic acid, and lower alkyl esters thereof,
and the like; or preferably, polyols, and especially preferably,
tetrols, such as pentaerythritol; triols, such as
trimethylolpropane; dihydroxy carboxylic acids; and
hydroxydicarboxylic acids and derivatives, such as dimethyl
hydroxyterephthalate, and the like. Branched poly(alkylene
terephthalate) resins and their preparation are described, for
example, in U.S. Pat. No. 3,953,404 to Borman. In addition to
terephthalic acid units, small amounts, e.g., from 0.5 to 15 mole
percent of other aromatic dicarboxylic acids, such as isophthalic
acid or naphthalene dicarboxylic acid, or aliphatic dicarboxylic
acids, such as adipic acid, can also be present, as well as a minor
amount of diol component other than that derived from
1,4-butanediol, such as ethylene glycol or cyclohexane dimethanol,
etc., as well as minor amounts of trifunctional, or higher,
branching components, e.g., pentaerythritol, trimethyl trimesate,
and the like.
[0049] In an embodiment, a PBT (for example a PET-derived PBT) is
used in combination with a poly(ethylene terephthalate),
poly(1,4-butylene terephthalate), poly(ethylene naphthalate),
poly(1,4-butylene naphthalate), poly(trimethylene terephthalate),
poly(1,4-cyclohexanenedimethylene 1,4-cyclohexanedicarboxylate),
poly(1,4-cyclohexanedimethylene terephthalate),
poly(1,4-butylene-co-1,4-but-2-ene diol terephthalate),
poly(cyclohexanedimethylene-co-ethylene terephthalate), or a
combination thereof. The weight ratio of PBT:other polyester can
vary from 50:50 to 99:1, specifically from 80:20 to 99:1.
[0050] Any of the foregoing first and optional second polyesters
can have an intrinsic viscosity of 0.4 to 2.0 deciliters per gram
(dL/g), measured in a 60:40 by weight
phenol/1,1,2,2-tetrachloroethane mixture at 23.degree. C. The PBT
can have a weight average molecular weight of 10,000 to 200,000
Daltons, specifically 50,000 to 150,000 Daltons as measured by gel
permeation chromatography (GPC). The polyester component can also
comprise a mixture of different batches of PBT prepared under
different process conditions in order to achieve different
intrinsic viscosities and/or weight average molecular weights. In
an embodiment, a combination of polyesters having different
viscosities is used, for example a combination comprising a first
polyester having a viscosity from 0.5 to 1.0 dL/g and a second
polyester having an intrinsic viscosity ranging from 1.1 to 1.4
dL/g. One or both of the polyesters can be a PBT, in particular a
PET-derived PBT. The weight ratio of the two polyesters of
different viscosity can be adjusted to achieve the desired
properties, and is generally within the range of 20:80 to 80:20,
more specifically from 40:60 to 60:40.
[0051] The amount of the polyester in the compositions can be
adjusted to provide the desired properties within the limits
described herein, which varies with the specific application. The
composition can accordingly comprise from 40 to 60 wt %,
specifically from 45 to 55 wt %, of the polyester, wherein each of
the foregoing is based on the total weight of the composition.
[0052] The composition includes a melamine flame retardant
synergist and a phosphinate flame retardant. It has been found that
this combination provides excellent flame retardance, in
combination with advantageous physical properties in the absence of
PEI. The flame retardant synergist is melamine pyrophosphate,
melamine polyphosphate, melamine phosphate, or melamine cyanurate.
Combinations comprising the foregoing can be used.
[0053] The flame retardant synergist is present in the composition
in an amount from 2 to 8 wt %, specifically from 3 to 7 wt %, still
more specifically from 4 to 6 wt %, each based on the total weight
of the composition.
[0054] The flame retardant synergist is used in combination with
one or more phosphinic acid salts. The phosphinates and
diphosphinates include those set forth in U.S. Pat. No. 6,255,371
to Schosser et al. The specification of this patent, column 1, line
46 to column 3 line 4 is incorporated by reference into the present
specification. Specific phosphinates mentioned include aluminum
diethylphosphinate (DEPAL), and zinc diethylphosphinate (DEPZN).
The phosphinates have the formulas
[(R.sup.1)(R.sup.2)(PO)--O].sub.m.sup.-M.sup.m+ (I) and
[(O--POR.sup.1)(R.sup.3)(POR.sup.2--O)].sup.2--O)].sup.2-.sub.nM.sup.m+.-
sub.x, (II),
and include polymers comprising such formula I or II, wherein
R.sup.1 and R.sup.2 are the same or different and are H,
C.sub.1-C.sub.6 alkyl, linear or branched, or C.sub.6-C.sub.10
aryl; and R.sup.3 is C.sub.1-C.sub.10, alkylene, linear or
branched, C.sub.6-C.sub.10 arylene, C.sub.7-C.sub.11 alkylarylene,
or C.sub.7-C.sub.11 arylalkylene; M is an alkaline earth metal,
alkali metal, Al, Ti, Zn, Fe, or boron; m is 1, 2, 3 or 4; n is 1,
2, or 3; and x is 1 or 2. In an embodiment R.sup.1 and R.sup.2 are
the same and are C.sub.1-C.sub.6-alkyl, linear or branched, or
phenyl; R.sup.3 is C.sub.1-C.sub.10-alkylene, linear or branched,
C.sub.6-C.sub.10-arylene,-alkylarylene or -arylalkylene; M is
magnesium, calcium, aluminum, zinc, or a combination thereof; m is
1, 2 or 3; n is 1, 2 or 3; and x is 1 or 2. R' and R.sup.2 can be
H, in addition to the substituents referred to set forth in the
patent. This results in a hypophosphite, a subset of phosphinate,
such as calcium hypophosphite, aluminum hypophosphite, and the
like.
[0055] In a specific embodiment M is aluminum, and R.sup.1 and
R.sup.2 are the same and are H, C.sub.1-C.sub.6 alkyl, linear or
branched; and R.sup.3 is C.sub.1-C.sub.10 alkylene, linear or
branched. A commercial example of a phosphinic acid salt includes
aluminum diethyl phosphinic acid (Al-DPA), commercially available
from Clariant Corp.
[0056] The composition comprises from 5 to 15 wt %, specifically
from 8 to 14 wt %, even more specifically from 10 to 12.5 wt % of a
flame retardant phosphinate salt, based on the total weight of the
composition.
[0057] The thermoplastic polyester composition also comprises a
reinforcing filler, for example rigid fibers such as glass fibers,
carbon fibers, metal fibers, ceramic fibers or whiskers, and the
like. Glass fibers typically have a modulus of greater than or
equal to about 6,800 megaPascals, and can be chopped or continuous.
The glass fiber can have various cross-sections, for example,
round, trapezoidal, rectangular, square, crescent, bilobal,
trilobal, and hexagonal. Glass fibers can be in the form of chopped
strands having an average length of from 0.1 mm to 10 mm, and
having an average aspect ratio of 2 to 5. In articles molded from
the compositions, shorter lengths will typically be encountered
because during compounding considerable fragmentation can
occur.
[0058] In some applications it can be desirable to treat the
surface of the fiber, in particular a glass fiber, with a chemical
coupling agent to improve adhesion to a thermoplastic resin in the
composition. Examples of useful coupling agents are alkoxy silanes
and alkoxy zirconates. Amino, epoxy, amide, or thio functional
alkoxy silanes are especially useful. Fiber coatings with high
thermal stability are preferred to prevent decomposition of the
coating, which could result in foaming or gas generation during
processing at the high melt temperatures required to form the
compositions into molded parts.
[0059] The reinforcing filler, for example a glass fiber, is
present in the composition in an amount from 25 to 35 wt %,
specifically from 20 to 40% by weight, and most preferably, from 25
to 35% by weight.
[0060] In still other embodiments, the compositions can optionally
additionally comprise a particulate (non-fibrous) organic filler,
which can impart additional beneficial properties to the
compositions such as thermal stability, increased density,
stifthess, and/or texture. Exemplary particulate fillers are
inorganic fillers such as alumina, amorphous silica, alumino
silicates, mica, clay, talc, glass flake, glass microspheres, metal
oxides such as titanium dioxide, zinc sulfide, ground quartz, and
the like.
[0061] In some embodiments, the reinforcing filler, for example
glass fibers, is used in combination with a flat, plate-like
filler, for example talc, mica or flaked glass. Typically, the
flat, plate-like filler has a length and width at least ten times
greater than its thickness, where the thickness is from 1 to about
1000 microns. Combinations of rigid fibrous fillers with flat,
plate-like fillers can reduce warp of the molded article. A
specific particulate filler is talc, in particular a talc filler
having an average largest dimension of less than 0.9 micrometers.
In addition, or in the alternative, the filler can have a median
particle size of less than 0.9 micrometers. In an embodiment, the
equivalent spherical diameter of the particle is used to determine
particle size. Use of these types of filler provides molded
articles having both low shrinkage and a smooth surface finish. Use
of these types of filler can also aid the crystallization of the
polyester, and increase heat resistance of the composition. Such
talcs are commercially available from Barretts Minerals Inc. under
the trade name ULTRATALC.RTM. 609.
[0062] When present, the particulate filler is used in an amount
from more than zero to 3 wt %, specifically more than 0 to 2 wt %,
more specifically from 0.1 to 1 wt %.
[0063] The composition further comprises a specific amount of a
specific combination of two types impact modifiers, a
poly(ether-ester)elastomer and a (meth)acrylate impact modifier. It
has surprising been found that use of only a single impact
modifier, or a combination of impact modifiers outside of the
specified range, adversely affects the desired combination of
properties. In a specific embodiment, no other impact modifiers are
present in the composition.
[0064] Poly(ester-ether)elastomers are copolymers that contain
"hard blocks" (derived from the polyester units) and "soft blocks"
(derived from the polyether units) that provide the polymer with
elastomeric properties. The copolymers can be characterized by the
melting temperature (Tm) of the hard block and the glass transition
temperature (Tg) of the soft block and. In general, the Tm of the
hard block can be 120 to 200.degree. C., specifically 150 to
195.degree. C., and the Tg of the soft block can be -25 to
-85.degree. C., specifically -45 to -65.degree. C.
[0065] The Poly(ester-ether)elastomers accordingly comprise units
derived from the reaction of a dicarboxylic acid component (or
chemical equivalent thereof) with two types of diols (or chemical
equivalent thereof), a short chain C1-10 diol, and a long-chain
poly(oxyalkylene)diol.
[0066] The dicarboxylic acid component can be one or more of the
dicarboxylic acids described above in connection with the
polyesters. In one embodiment, the dicarboxylic acid is aromatic,
for example terephthalic acid, isophthalic acid, or a combination
comprising at least one of the foregoing acids. In a specific
embodiment, the dicarboxylic acid is terephthalic acid. In another
embodiment, the dicarboxylic acid is a combination of terephthalic
acid and isophthalic acid.
[0067] Suitable short chain diols include C1-8 diols as described
above in connection with the polyester. Specific diols are ethylene
glycol and butane diol, even more specifically butane diol.
[0068] The poly(oxyalkylene)diol is derived from the polymerization
of a C1-6 diol or a combination comprising one or more C.sub.1-6
diols, in particular C.sub.2-4 diols, or the chemical equivalents
thereof. Poly(oxytetramethylene)glycol is preferred, and can be
prepared by well known techniques. The poly(oxyalkylene)diol, in
particular the poly(oxytetramethylene)glycol, has a weight average
molecular weight (Mw) of 100 to 5,000, or more specifically, 150 to
4,000, or even more specifically, 200 to 3,000.
[0069] The poly(ether-ester)elastomers can accordingly comprise
long-chain ester units of formula (III):
-GOC(O)R'C(O)O-- (III);
and short-chain ester units having units of formula (IV):
-DOC(O)R'C(O)O-- (IV),
wherein R' is a divalent aromatic radical remaining after removal
of carboxyl groups from terephthalic acid, isophthalic acid, or a
combination of terephthalic acid and isophthalic acid; G is s
divalent polyalkylene oxide radical remaining after removal of
terminal hydroxyl groups from a poly(alkylene oxide)glycol having a
number-average molecular weight of 100 to 2500 Daltons; and D is
the divalent alkylene radical remaining after removal of hydroxyl
groups from an aliphatic diol having a molecular weight from 62 to
286.
[0070] A specific poly(ester-ether)elastomers is a poly(butylene
terephthalate/isophthalate-oxytetramethylene)copolymer, i.e., a
poly(butylene terephthalate-polytetrahydrofuran) block copolymer.
The copolymer comprises 25 to 65 wt %, more specifically 30 to 60
wt %, even more specifically 25 to 55 wt % of units derived from
poly(oxytetramethylene)glycol or chemical equivalents thereof,
based on the weight of the copolymer.
[0071] The poly(butylene terephthalate-oxytetramethylene)copolymer
can further comprise isophthalic acid in addition to terephthalic
acid. In one embodiment, the poly(butylene
terephthalate/isophthalate-oxytetramethylene)copolymer comprises 0
to 40 mole % of units derived from isophthalic acid or a chemical
equivalent thereof, based on the total number of isophthalate and
terephthalate units. For example, the poly(butylene
terephthalate/isophthalate-oxytetramethylene)copolymer can comprise
less than 5 mole % of isophthalate units, specifically 0 to 5 mole
% of isophthalate units, based on the total number of isophthalate
and terephthalate units in the copolymer. In another embodiment,
the poly(butylene
terephthalate/isophthalate-oxytetramethylene)copolymer comprises
greater than 5 mole % of isophthalate units, specifically 5 to 40
mole %, based on the total number of isophthalate and terephthalate
units in the copolymer.
[0072] A variety of poly(ether-ester)copolymers are commercially
available, for example under the trademarks ARNITEL EM400 and
ARNITEL EL630 poly(ether-ester)copolymers from DSM; HYTREL 3078,
HYTREL 4056, HYTREL 4556, and HYTREL 6356
poly(ether-ester)copolymers from DuPont; and ECDEL 9966
poly(ether-ester)copolymer from Eastman Chemical. In all cases, the
soft block is derived from tetrahydrofuran. In the HYTREL 4556,
HYTREL 6356, ARNITEL EM400, and ARNITEL EL630
poly(ether-ester)copolymers, the hard block is based on
poly(butylene terephthalate) (PBT). In the HYTREL 4056
poly(ether-ester)copolymer, the hard block contains isophthalate
units in addition to terephthalate units. In the ECDEL 9966
poly(ether-ester)copolymer, the hard block is based on
poly(1,4-cyclohexane-dimethanol-1,4-cyclohexane dicarboxylate)
(PCCD) units. In another embodiment, the poly(ether-ester)elastomer
can include a thermoplastic copolyetherester elastomer derived from
polyethylene terephthalate, in particular, post-consumer
polyethylene terephthalate. The random copolyetherester contains a
modified, random polybutylene terephthalate copolymer block that is
derived from a polyethylene terephthalate component selected from
the group consisting of polyethylene terephthalate and polyethylene
terephthalate copolymers, or a combination thereof; and contains at
least one residue derived from the polyethylene terephthalate
component; and a polyalkylene oxide copolymer block that is derived
from a polyethylene terephthalate component and polyalkylene oxide
glycol, and contains polyalkylene oxide and at least one residue
derived from the polyethylene terephthalate component. Such random
copolyetheresters are disclosed in U.S. Publ. 2008/0027167, and is
commercially available under the trademark VALOX iQ elastomer,
which can be available from SABIC Innovative Plastics.
[0073] The impact modifier component also comprises a
(meth)acrylate impact modifier. A (meth)acrylate impact modifier
includes graft and/or core shell structures having a rubbery
component with a Tg below 0.degree. C., preferably between about
-40.degree. to about -80.degree. C., and which include a
poly(alkyl(meth)acrylate) or polyolefin grafted with a poly(methyl
methacrylate) or styrene-acrylonitrile copolymer.
[0074] Typical core materials in core-shell impact modifiers
consist substantially of a (meth)acrylate rubber, for example a
(meth)acrylate rubber of derived from a C4-12 acrylate. Typically,
one or more shells are grafted on the core. Usually these shells
are built up from a vinyl aromatic compound, a vinyl cyanide, an
alkyl(meth)acrylate, (meth)acrylic acid, or a combination thereof.
The shell can be derived from an alkyl(meth)acrylate, more
specifically a methyl(meth)acrylate. The core and/or the shell(s)
often comprise multi-functional compounds that can act as a
cross-linking agent and/or as a grafting agent. In one embodiment,
the (meth)acrylate impact modifier has a crosslinked poly(butyl
acrylate) core with a grafted poly(methyl methacrylate) shell.
[0075] Core-shell acrylic rubbers can be of various particle sizes,
for example from 300-800 nm, although larger particles, or mixtures
of small and large particles, can also be used. In some instances,
(meth)acrylate impact modifier with a particle size of 350-450 nm
is used. In other applications where higher impact is desired,
particle sizes of 450-550 nm or 650-750 nm can be used.
[0076] Specific (meth)acrylate impact modifiers include the
core-shell polymers available from Rohm & Haas (now Dow
Advanced Materials) under the trade name PARALOID.RTM., including,
for example, PARALOID.RTM. EXL3691 and PARALOID.RTM. EXL3330,
EXL3300 and EXL2300.
[0077] Other (meth)acrylate impact modifiers include
ethylene-acrylic acid copolymers (EEA), sold by Dupont under the
trade name ELVALOY; ethylene-methacrylate-glycidyl methacrylate
copolymers (E-GMA-MA), sold by Arkema under the trade name
LOTADER.RTM.; and polyethylene-g-glycidyl methacrylate (10%), sold
by Sumitomo Chemical Co. under the trade name IGETABOND E.
[0078] The impact modifier component is present in the composition
in an amount from more than 0 to less than 5 wt %, specifically
from 2 to 2.5 wt %.
[0079] In a specific embodiment, the impact modifier component
comprises from more than 0 to 5 wt %, specifically from 2 to 4 wt
%, of a combination of (i) a poly(butylene
terephthalate-polytetrahydrofuran) block copolymer and (ii) a
core-shell impact modifier having a crosslinked poly(butyl
acrylate) core with a grafted poly(methyl methacrylate) shell.
[0080] The polyester compositions further comprise from more than 0
to 5 wt %, specifically from 0.5 to 5 wt % of an encapsulated
particulate fluoropolymer, in particular poly(tetrafluoroethylene)
encapsulated by a styrene-acrylonitrile copolymer.). Small amounts
of other fluoropolymers can be used, for example those comprising
units derived from fluorinated monomers such as
3,3,3-trifluoropropene, 3,3,3,4,4-pentafluoro-1-butene,
hexafluoropropylene, vinyl fluoride; vinylidene fluoride,
1,2-difluoroethylene, and the like, or a mixture comprising at
least one of the foregoing monomers
[0081] The fluoropolymer is encapsulated styrene-acrylonitrile
(SAN). PTFE encapsulated in styrene-acrylonitrile is also known as
TSAN.
[0082] Encapsulated fluoropolymers can be made by polymerizing the
encapsulating polymer in the presence of the fluoropolymer, for
example an aqueous dispersion of the fluoropolymer. Alternatively,
the fluoropolymer can be pre-blended with a second polymer, such as
for, example, an aromatic polycarbonate or SAN to form an
agglomerated material. Either method can be used to produce an
encapsulated fluoropolymer. The relative ratio of monovinyl
aromatic monomer and monovinylic comonomer in the rigid graft phase
can vary widely depending on the type of fluoropolymer, type of
monovinylaromatic monomer(s), type of comonomer(s), and the desired
properties of the composition. The rigid phase can comprise 10 to
95 wt % of monovinyl aromatic monomer, specifically about 30 to
about 90 wt %, more specifically 50 to 80 wt % monovinylaromatic
monomer, with the balance of the rigid phase being comonomer(s).
The SAN can comprise, for example, about 75 wt % styrene and about
25 wt % acrylonitrile based on the total weight of the copolymer.
An exemplary TSAN comprises about 50 wt % PTFE and about 50 wt %
SAN, based on the total weight of the encapsulated
fluoropolymer.
[0083] The molding composition can optionally comprise a small
amount of a charring polymer, in particular a polyetherimide (PEI).
A commercially available polyetherimide is available from SABIC
Innovative Plastics Co. under the trade name ULTEM.RTM. 1010. Other
charring polymers include, poly(phenylene ether),
poly(phenylenesulfide), polysulphones, polyethersulphones,
poly(phenylenesulphide oxide) (PPSO), and polyphenolics (e.g.,
novolacs). Use of a polyetherimide in compositions comprising
aluminum phosphinate salts can improve the mechanical properties of
the compositions, in particular tensile strength and impact
properties. High temperature molding stability can also be further
improved, as well as melt stability.
[0084] The charring polymer, in particular PEI, can accordingly be
present in an amount from 0 to less than 5 wt % of the composition,
more specifically from more than 0 to less than 3 wt %, by even
more specifically from more than 0 to less than 1 wt %, based on
the total weight of the composition.
[0085] However, in a unique advantage of the current compositions,
improvement in flexural modulus, notched and unnotched Izod impact
strength, tensile stress at break and/or elastic modulus, and high
CTI is observed when the composition comprises no polyetherimide.
Thus, in one embodiment, no polyetherimide is present. In another
embodiment, no charring polymer is present. In an embodiment
wherein the composition contains no polyetherimide, an article
molded from the composition exhibits a CTI (Comparative Tracking
Index) of 600 volts.
[0086] A stabilizer component is further present in the
composition, in an amount from more than 0 to 2 wt %, specifically
0.01 to 1 wt %, even more specifically 0.05 to 0.5 wt %. As used
herein, a "stabilizer" is inclusive of an antioxidant, thermal
stabilizer, radiation stabilizer, ultraviolet light absorbing
additive, and the like, and combinations thereof In one embodiment
the stabilizer component comprises an antioxidant.
[0087] Exemplary antioxidants include organophosphites such as
tris(nonyl phenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite,
bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearyl
pentaerythritol diphosphite; alkylated monophenols or polyphenols;
alkylated reaction products of polyphenols with dienes, such as
tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane;
butylated reaction products of para-cresol or dicyclopentadiene;
alkylated hydroquinones; hydroxylated thiodiphenyl ethers;
alkylidene-bisphenols; benzyl compounds; esters of
beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with
monohydric or polyhydric alcohols; esters of
beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid with
monohydric or polyhydric alcohols; esters of thioalkyl or thioaryl
compounds such as distearylthiopropionate, dilaurylthiopropionate,
ditridecylthiodipropionate,
octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,
pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;
amides of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid,
or combinations comprising at least one of the foregoing
antioxidants. A specific antioxidant is a hindered phenol
stabilizer, pentaerythritol
tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate), sold under the
trade name IRGANOX.RTM. 1010 from Ciba Specialty Chemicals.
[0088] Exemplary heat stabilizer additives include organophosphites
such as triphenyl phosphite, tris-(2,6-dimethylphenyl)phosphite,
tris-(mixed mono-and di-nonylphenyl)phosphite; phosphonates such as
dimethylbenzene phosphonate, phosphates such as trimethyl
phosphate, or combinations comprising at least one of the foregoing
heat stabilizers. Heat stabilizers are used in amounts of 0.01 to
0.1 parts by weight, based on 100 parts by weight of the total
composition, excluding any filler.
[0089] Light stabilizers and/or ultraviolet light (UV) absorbing
additives can also be used. Exemplary light stabilizer additives
include benzotriazoles such as
2-(2-hydroxy-5-methylphenyl)benzotriazole,
2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole and
2-hydroxy-4-n-octoxy benzophenone, or combinations comprising at
least one of the foregoing light stabilizers. Light stabilizers are
used in amounts of 0.01 to 5 parts by weight, based on 100 parts by
weight of the total composition, excluding any filler.
[0090] Exemplary UV absorbing additives include
hydroxybenzophenones; hydroxybenzotriazoles; hydroxybenzotriazines;
cyanoacrylates; oxanilides; benzoxazinones;
2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol
(CYASORB.RTM. 5411); 2-hydroxy-4-n-octyloxybenzophenone
(CYASORB.RTM. 531);
2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phe-
nol (CYASORB.RTM. 1164);
2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one) (CYASORB.RTM.
UV-3638);
1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenyl-
acryloyl)oxy]methyl]propane (UVINUL.RTM. 3030);
2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one);
1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenyl-
acryloyl)oxy]methyl]propane; nano-size inorganic materials such as
titanium oxide, cerium oxide, and zinc oxide, all with particle
size less than or equal to 100 nanometers, or combinations
comprising at least one of the foregoing UV absorbers. UV absorbers
are used in amounts of 0.01 to 5 parts by weight, based on 100
parts by weight of the total composition, excluding any filler.
[0091] With the proviso that flame retardance properties and
mechanical properties such as impact strength and flexural modulus
are not significantly adversely affected, the compositions can
further comprise other conventional additives used in polyester
polymer compositions such as mold release agents, plasticizers,
quenchers, lubricants, antistatic agents, processing aids, dyes,
pigments, laser marking additives, and the like. A combination
comprising one or more of the foregoing or other additives can be
used. Plasticizers, lubricants, and/or mold release agents can be
specifically mentioned. There is considerable overlap among these
types of materials, which include phthalic acid esters such as
dioctyl-4,5-epoxy-hexahydrophthalate;
tris-(octoxycarbonylethyl)isocyanurate; tristearin; di- or
polyfunctional aromatic phosphates such as resorcinol tetraphenyl
diphosphate (RDP), the bis(diphenyl) phosphate of hydroquinone and
the bis(diphenyl) phosphate of bisphenol A; poly-alpha-olefins;
epoxidized soybean oil; silicones, including silicone oils; esters,
for example, fatty acid esters such as alkyl stearyl esters, e.g.,
methyl stearate, stearyl stearate, pentaerythritol tetrastearate,
and the like; combinations of methyl stearate and hydrophilic and
hydrophobic nonionic surfactants comprising polyethylene glycol
polymers, polypropylene glycol polymers, poly(ethylene
glycol-co-propylene glycol)copolymers, or a combination comprising
at least one of the foregoing glycol polymers, e.g., methyl
stearate and polyethylene-polypropylene glycol copolymer in a
solvent; waxes such as beeswax, montan wax, and paraffin wax. Such
materials are used in amounts of 0.1 to 1 parts by weight, based on
100 parts by weight of the total composition, excluding any filler.
An exemplary mold release agent is pentaerythritol tetrastearate,
available from Faci SpA.
[0092] The compositions can be prepared by blending the components
of the composition, employing a number of procedures. In an
exemplary process, the polyester component, reinforcing filler,
melamine flame retardant synergist, phosphinate salt flame
retardant, impact modifier component, poly(tetrafluoroethylene)
encapsulated by a styrene-acrylonitrile copolymer, stabilizer, and
optionally polyetherimide are placed into an extrusion compounder
to produce molding pellets. The components are dispersed in a
matrix in the process. In another procedure, the components and
reinforcing filler are mixed by dry blending, and then fluxed on a
mill and comminuted, or extruded and chopped. The composition and
any optional components can also be mixed and directly molded,
e.g., by injection or transfer molding techniques. Preferably, all
of the components are freed from as much water as possible. In
addition, compounding is carried out to ensure that the residence
time in the machine is short; the temperature is carefully
controlled; the friction heat is utilized; and an intimate blend
between the components is obtained.
[0093] The components can be pre-compounded, pelletized, and then
molded. Pre-compounding can be carried out in conventional
equipment. For example, after pre-drying the polyester composition
(e.g., for four hours at 120.degree. C.), a single screw extruder
can be fed with a dry blend of the ingredients, the screw employed
having a long transition section to ensure proper melting.
Alternatively, a twin screw extruder with intermeshing co-rotating
screws can be fed with resin and additives at the feed port and
reinforcing additives (and other additives) can be fed downstream.
In either case, a generally suitable melt temperature will be
230.degree. C. to 300.degree. C. The pre-compounded composition can
be extruded and cut up into molding compounds such as conventional
granules, pellets, and the like by standard techniques. The
composition can then be molded in any equipment conventionally used
for thermoplastic compositions, such as a Newbury or van Dorn type
injection molding machine with conventional cylinder temperatures,
at 230.degree. C. to 280.degree. C., and conventional mold
temperatures at 55.degree. C. to 95.degree. C. The molded
compositions provide an excellent balance of impact strength and
flame retardancy.
[0094] In particular, the compositions provide excellent flame
retardancy when molded into either thick or thin components. One
set of test conditions commonly accepted and used as a standard for
flame retardancy is set forth in Underwriters Laboratories, Inc.
Bulletin 94, which prescribes certain conditions by which materials
are rated for self-extinguishing characteristics. Another set of
conditions commonly accepted and used (especially in Europe) as a
standard for flame retardancy is the Glow Wire Ignition Test
(GWIT), performed according to the International standard IEC
695-2-1/2. A 0.8 mm thick molded sample comprising the composition
can have a UL-94 flammability rating of V0.
[0095] An article can be molded from the thermoplastic polyester
composition as described above. The article can include computer
fans, electrical connectors, automotive battery housings, and
lighting sockets.
[0096] A molded article comprising the composition can have a
flexural modulus of from 3000 MPa to 20000 MPa, more specifically
more than 9800 MPa to 20000 MPa, measured in accordance with ASTM
790, and the flexular stress at break can be from 120 to 200 MPa,
more specifically 130 to 190 MPa, even more specifically more than
150 MPa to 190 MPa, measured in accordance with ASTM 790.
[0097] A molded article comprising the composition can have good
impact properties, for example, an unnotched Izod impact strength
from to 300 to 700 J/m, more specifically, more than 470 J/m to 700
J/m, as measured at 23.degree. C. in accordance with ASTM D256.
[0098] In a specific embodiment, the glass-filled, chlorine- and
bromine-free poly(alkylene ester) flame retardant composition
containing a combination of impact modifiers can have a combination
of highly useful physical properties, namely, good flame retardance
performance (e.g., a rating of V0 at 0.80 mm), higher CTI
performance, improved impact properties and improved flexural
properties, as compared to a glass-filled, chlorine and
bromine-free poly(alkylene ester) flame retardant composition that
contains polyimide but no elastomers. More specifically, the
compositions containing a combination of elastomers can meet
targeted performance properties, namely: (a) a flexural modulus
greater than 9800 MPa, (b) a flexural stress greater than 150 MPa,
(c) an unnotched impact strength greater than 470 Joules/meter, and
(d) a rating of V0 at a thickness of 0.8 mm, measured in accordance
with the UL 94 protocol.
[0099] For example, an article molded from the following
thermoplastic polyester composition exhibits (a) a flexural modulus
that is more than 9800 MPa, (b) a flexural stress is more than 150
MPa, (c) an unnotched impact strength that is more than 470
Joules/meter, and (d) a V0 rating at 0.8 mm, measured in accordance
with UL 94, when the composition comprises, based on the weight of
the composition, a combination of: (a) from 40 to 60 wt % of
polybutylene terephthalate; (b) from 25 to 35 wt % glass fiber
filler; (c) from 2 to 8 wt % of a flame retardant synergist
selected from the group consisting of melamine polyphosphate,
melamine cyanurate, melamine pyrophosphate, melamine phosphate, and
combinations thereof; (d) from more than 10 to 15 wt % a
phosphinate of formula (I) described herein a diphosphinate of
formula (II) described herein, and/or a polymer derived from the
phosphinate of formula (I) or the diphosphinate of the formula
(II), (e) at least 1 to less than 5 wt % of impact modifier
component comprising a combination of (i) a poly(butylene
terephthalate-polytetrahydrofuran) block copolymer and (ii) a
core-shell (meth)acrylate impact modifier having a crosslinked
poly(butyl acrylate) core with a grafted poly(methyl methacrylate)
shell; (f) from more than 0 to 5 wt % poly(tetrafluoroethylene)
encapsulated by a styrene-acrylonitrile copolymer; and (g) from
more than 0 wt % to 2 wt % of a stabilizer; wherein the halogen
free composition contains less than 2 wt % of a polyetherimide.
[0100] Advantageously, it is now possible to make gas filled
halogen free flame retarding compositions that exhibit good flame
retardancy performance (i.e., V0 at 0.80 mm), higher CTI
performance, improved impact properties and improved flexural
properties. Our invention provides an eco-FR thermoplastic
polyester composition having good flame retardant properties and
comparable or improved mechanical properties, including ductility,
flexural strength, CTI, and stiffness relative to compositions
comprising halogenated flame retardants and eco-FR compositions
comprising PEI.
[0101] It should be clear that the compositions and articles
disclosed herein can include reaction products of the above
described components used in forming the compositions and
articles.
[0102] The invention is further illustrated by the following
non-limiting examples, in which all parts are by weight unless
otherwise stated.
EXAMPLES
[0103] The following materials were used in Examples 1 to 8 (i.e.,
E1 to E8) and Comparative Examples 1 to 25 (i.e., CE1 to CE25).
Table 1 shows the nomenclature used as well as a description. All
amounts in the following Tables are weight percent, unless
indicated otherwise.
TABLE-US-00001 TABLE 1 Abbreviation, Description and Sources of
Materials used in Examples Abbreviation Description Source VALOX
iQ* Intrinsic viscosity = 1.19 dl/g, SABIC Innovative PBT-1 Mn =
110,000 g/mol Plastics Company VALOX iQ*- Intrinsic viscosity =
0.66 dl/g, SABIC Innovative PBT-2 Mn = 53400 g/mol Plastics Company
Glass Fiber 13-micron diameter PPG Industries MPP Melamine
polyphosphate Ciba Specialty Al-DPA Aluminum diethyl phosphinic
Clariant acid PEI Polyetherimide (ULTEM 1010) SABIC Innovative
Plastics Company TSAN SAN encapsulated PTFE SABIC Innovative
Plastics Company AO Hindered phenol stabilizer Ciba Specialty PETS
Pentaerythritol tetrastearate Faci SpA ULTRATALC Talc (avg particle
size <0.90 Barretts micrometer) ELVALOY Ethylene-ethyl acrylate
Dupont 2615 AC copolymer IGETABOND E Polyethylene-g-glycidyl
Sumitomo methacrylate (10%) LOTADER E-GMA-MA Arkema HYTREL
Poly(butylene tere/iso phthalate- Dupont co-polyoxybutylene)
PARALOID Acrylic polymer impact modifier Rohm & Haas EXL VALOX
iQ* Thermoplastic poly(ether-ester) SABIC Innovative Elastomer**
elastomer Plastics Company *Trademark of SABIC Innovative Plastics
IP B.V. **The VALOX iQ thermoplastic poly(ether-ester) elastomer
used was a polybutylene terephthalate-based poly(ester-ether)
derived from post-consumer polyethylene terephthalate, as disclosed
in US Publ. 2008/0027167. The poly(ester-ether) copolymer comprises
units derived from terephthalic or a chemical equivalent thereof,
units derived from butane diol or a chemical equivalent thereof,
and 23 to 70 weight percent of units derived from
poly(oxytetramethylene) glycol or a chemical equivalent thereof,
based on the weight of the copolymer.
Techniques and Procedures
[0104] Extrusion/Molding Procedures. The components as shown in
Table 1 were tumble blended and then extruded on a 27-mm twin-screw
extruder with a vacuum vented mixing screw, at a barrel and die
head temperature of 240.degree. C.-265.degree. C. and a screw speed
of 300 rpm. The extrudate was cooled through a water bath before
pelletizing. ASTM Izod and flexural bars were injection molded on a
van Dorn molding machine with a set temperature of approximately
240.degree. C. to 265.degree. C. The pellets were dried for 3 to 4
hours at 120.degree. C. in a forced air-circulating oven before
injection molding.
[0105] Un-notched Izod Testing/Flexural Testing/Flame Testing.
Un-notched Izod testing was performed on 75 mm.times.12.5
mm.times.3.2 mm bars in accordance with ASTM D256. Flexural
properties were measured in accordance with ASTM 790 on molded
samples having a thickness of 3.2 mm. Flame testing per UL 94
protocol was conducted on flame bars with 0.80 mm thickness after
both 23.degree. C./48 hr and 70.degree. C./168 hr aging
conditions.
[0106] CTI Testing Procedures. CTI was used to measure the
electrical breakdown (tracking) properties of the test material. In
order to test for CTI, a specimen (2.54 cm diameter disk or larger)
was molded from the pellets and placed on a support. Two
electrodes, 4 mm apart, touched the specimen surface. A solution of
0.1% ammonium chloride electrolyte solution was introduced via a
syringe. One drop fell every 30 seconds on the surface between the
electrodes. The test proceeded by setting the electrodes to a fixed
applied voltage between 100 volts to 600 volts, and turning the
syringe pump on. The voltage that caused failure at 50 drops of
electrolytes was selected as a measure of susceptibility of a
material to tracking. Interpolation was used if necessary to obtain
this voltage. Performance Level Categories (PLC) were used to avoid
excessive implied precision and bias. The relationship between
tracking index voltage and PLC is shown in Table 2.
TABLE-US-00002 TABLE 2 Relationship between tracking index and PLC
Tracking Index (V) PLC Rating 600 and Greater 0 400 through 599 1
250 through 399 2 175 through 249 3 100 through 174 4 <100 5
Examples 1-8; Comparatives Examples 1-2
[0107] The purpose of Examples 1-8 was to make a glass-filled,
chlorine and bromine-free poly(alkylene)ester composition
containing a combination of elastomers and evaluate their
performance with regard to the following properties: (i) flame
retardance performance (i.e., V0 at 0.80 mm), (ii) CTI performance,
(iii) impact properties and (iv) flexural properties. These
compositions were evaluated to determine whether they certain
minimum targeted performance properties, namely: (a) a flexural
modulus greater than 9800 MPa, (b) a flexural stress greater than
150 MPa, (c) an unnotched impact strength greater than 470
Joules/meter, and (d) a rating of V0 at a thickness of 0.8 mm,
measured in accordance with the UL 94 protocol.
[0108] The purpose of Comparative Examples 1-2 was compare the
performance properties of the compositions of Examples 1-8 with (i)
a glass-filled, chlorine and bromine-free poly(alkylene ester)
flame retardant composition that contained polyimide but no
elastomers (Comparative Example 1) and (ii) a glass-filled,
chlorine and bromine-free poly(alkylene ester) flame retardant
composition that contained no polyimide and no elastomers
(Comparative Example 2).
[0109] Examples were prepared and tested as described above. The
results for Examples 1-8 are summarized in Table 3 and the results
for Comparative Examples 1-2 are summarized in Table 4.
TABLE-US-00003 TABLE 3 Formulation and physical properties of 30%
glass-filled, chlorine- and bromine- free, flame retardant
poly(alkylene ester) compositions (Examples 1 to 8) Targeted Unit
Performance E1 E2 E3 E4 E5 E6 E7 E8 Component VALOX iQ % 24.83
24.83 24.83 24.58 24.58 24.58 25.58 25.33 PBT-1 VALOX iQ % 24.83
24.83 24.83 24.58 24.58 24.58 25.58 25.33 PBT-2 Glass Fiber % 30.00
30.00 30.00 30.00 30.00 30.00 30.00 30.00 MPP % 5.00 5.00 5.00 5.00
5.00 5.00 5.00 5.00 Al-DPA % 12.50 12.50 12.50 12.50 12.50 12.50
11.00 11.00 TSAN % 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 AO %
0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 PETS % 0.20 0.20 0.20 0.20
0.20 0.20 0.20 0.20 ULTRATALC % 0.50 PEI (ULTEM % 1010) VALOX iQ %
1.50 1.25 1.88 1.50 1.50 Elastomer Resin HYTREL % 1.00 1.50 1.88
PARALOID % 1.00 0.50 0.50 0.63 1.25 0.63 0.50 0.50 EXL EEA %
IGETABOND E % LOTADER % 100 100 100 100 100 100 100 100 Test
Description Flexural MPa >9800 9935 9955 10030 10300 10500 10400
9990 9820 Modulus Flexural Stress MPa >150 157 158 154 157 160
154 158 157 at Break Izod Impact J/m >470 493 505 486 518 499
474 476 568 strength, Un- Notched Flame Rating - 0.80 mm V0 V0 V0
V0 V0 V0 V0 V0 V0 UL 94, 23.degree. C./48 hr Flame Rating - 0.80 mm
V0 V0 V0 V0 V0 V0 V0 V0 V0 UL 94, 70.degree. C./168 hr CTI (100) V
600 600 600 -- -- -- 600 600 CTI PLC Rating 0 0 0 -- -- -- 0 0
TABLE-US-00004 TABLE 4 Formulation and physical properties of
glass-filled, chlorine- and bromine-free, flame retardant
poly(alkylene ester) compositions (Comparative Examples 1 to 2)
Targeted Component Unit Performance CE1 CE2 VALOX iQ PBT-1 % 25.83
25.83 VALOX iQ PBT-2 % 25.83 25.83 Glass Fiber % 25.00 30.00 MPP %
5.00 5.00 Al-DPA % 12.50 12.50 TSAN % 0.50 0.50 AO % 0.15 0.15 PETS
% 0.20 0.20 ULTRATALC % PEI (ULTEM 1010) % 5.00 VALOX iQ Elastomer
Resin % HYTREL % PARALOID EXL % EEA % IGETABOND E % LOTADER % 100
100 Test Description Unit CE1 CE2 Flexural Modulus MPa >9800
9670 10100 Flexural Stress at Break MPa >150 160 150 Izod Impact
strength, J/m >470 432 410 Un-Notched Flame Rating - UL 94, 0.80
mm V0 V0 V0 23.degree. C./48 hr Flame Rating - UL 94, 0.80 mm V0 V0
V0 70.degree. C./168 hr CTI (100) V 250 -- CTI PLC Rating 2 --
Discussion
[0110] The results shown in Tables 3 and 4 indicate that it is
possible to make a glass-filled, chlorine- and bromine-free
poly(alkylene ester) flame retardant composition containing a
combination of elastomers with useful properties, namely, good
flame retardance performance (i.e., a rating of V0 at 0.80 mm),
higher CTI performance, improved impact properties and improved
flexural properties, as compared to a glass-filled, chlorine and
bromine-free poly(alkylene ester) flame retardant composition that
contains polyimide but no elastomers. More particularly, the
results of Examples 1-8 showed that the inventive compositions meet
the minimum targeted performance properties, namely: (a) a flexural
modulus greater than 9800 MPa, (b) a flexural stress greater than
150 MPa, (c) an unnotched impact strength greater than 470
Joules/meter, and (d) a rating of V0 at a thickness of 0.8 mm,
measured in accordance with the UL 94 protocol. The compositions of
Comparative Examples 1-2 did not meet these properties.
[0111] It can be seen that in Examples El to E8 in Table 3, when no
ULTEM 1010 was present in the formulations and glass fiber content
was 30%, the addition of combinations of elastomers (HYTREL/VALOX
iQ Elastomer and PARALOID EXL) at a 2 wt % level (El (1% HYTREL and
1% PARALOID EXL), E2 (1.5% HYTREL and 0.5% PARALOID EXL) and E3,
E7, and E8 (1.5% VALOX iQ Elastomer and 0.5% PARALOID EXL)) and 2.5
wt % level (E4 (1.88% HYTREL and 0.63% PARALOID EXL), E5 (1.25%
VALOX iQ Elastomer and 1.25% PARALOID EXL), and E6 (1.88% VALOX iQ
Elastomer and 0.63% PARALOID EXL)) can improve mechanical
properties such as unnotched Izod impact strength by at least 8.8%,
while maintaining flame retardance performance (V0 at 0.8 mm) per
UL 94, compared with CE1. Furthermore, the CTIs of E1, E2, E3, E7,
and E8 are also in much higher voltages than CE1: 600 V for E1, E2,
E3, E7, and E8 as compared to 250 V for CE1. This is equivalent to
a 2 PLC rating increase. Furthermore, when less Al-DPA was used in
E7 and E8 (11%) as compared with in CE1 (12.5%), a UL 94 V0 rating
at 0.80 mm was still achieved. Especially in E8, where 0.5%
ULTRATALC is present in the formulation, the unnotched impact
strength (568 J/m) was largely improved from the 438 J/m observed
for CE1, as well as the 476 J/m of E7.
[0112] As shown in the comparative examples (Table 4), CE1 was a 25
wt % glass and 5 wt % polyimide (ULTEM 1010)-filled, chlorine- and
bromine-free poly(alkylene ester) flame retardant composition. CE2
was a 30 wt % glass-filled, chlorine- and bromine-free
poly(alkylene ester) flame retardant composition with no polyimide
(ULTEM 1010). When the 5 wt % ULTEM 1010 in CE1 was replaced with 5
wt % glass in CE2, the unnotched Izod impact strength of the
formulation dropped by 5% (from 432 to 410 J/m), even though the
same V0 rating was achieved. The low impact strength of CE2 limits
its use in applications such as electrical connectors and computer
fans.
Comparative Examples 3-25
[0113] The purpose of Comparative Examples 3-25 was to compare the
performance of compositions containing a single elastomer with
compositions having a combination of elastomers, as well as the
performance of compositions containing a combination of elastomers
in amounts outside the inventive ranges.
[0114] Examples were prepared and tested as described above. The
results for Comparative Examples CE3-CE25 are shown in Tables 5, 6,
and 7.
TABLE-US-00005 TABLE 5 Formulation and physical properties of
glass-filled, chlorine- and bromine-free, flame retardant
poly(alkylene ester) compositions (Comparative Example 3 to 12)
Targeted Perform- Unit ance CE3 CE4 CE5 CE6 CE7 CE8 CE9 CE10 CE11
CE12 Component VALOX iQ % 23.33 23.33 23.33 23.33 23.33 23.33 23.33
23.33 23.33 23.83 PBT-1 VALOX iQ % 23.33 23.33 23.33 23.33 23.33
23.33 23.33 23.33 23.33 23.83 PBT-2 Glass Fiber % 30.00 30.00 30.00
30.00 30.00 30.00 30.00 30.00 30.00 30.00 MPP % 5.00 5.00 5.00 5.00
5.00 5.00 5.00 5.00 5.00 5.00 Al-DPA % 12.50 12.50 12.50 12.50
12.50 12.50 12.50 12.50 12.50 11.00 TSAN % 0.50 0.50 0.50 0.50 0.50
0.50 0.50 0.50 0.50 0.50 AO % 0.15 0.15 0.15 0.15 0.15 0.15 0.15
0.15 0.15 0.15 PETS % 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20
0.20 ULTRATALC % -- -- -- -- -- -- -- -- -- 0.50 PEI (ULTEM % -- --
-- -- -- -- -- -- -- -- 1010) VALOX iQ % -- -- -- -- -- -- -- 2.50
3.75 3.75 Elastomer Resin HYTREL % 5.00 -- -- -- -- 2.50 3.75 -- --
-- PARALOID % -- 5.00 -- -- 2.50 1.25 2.50 1.25 1.25 EXL EEA % --
-- 5.00 -- -- -- -- -- -- -- IGETABOND E % -- -- -- 5.00 -- -- --
-- -- -- LOTADER % -- -- -- -- 5.00 -- -- -- -- -- 100 100 100 100
100 100 100 100 100 100 Test Description Flexural MPa >9800 8570
9420 8820 8610 8370 9840 9700 9810 9420 9410 Modulus Flexural MPa
>150 119 137 126 143 138 147 144 146 142 147 Stress at Break
Izod Impact J/m >470 442 398 412 461 452 464 482 529 557 494
strength, Un- Notched Flame Rating - 0.80 mm V0 V0 V0 V0 V0 V0 V0
V0 V0 V0 V0 UL 94, 23.degree. C./48 hr Flame Rating - 0.80 mm V0 V0
V0 V0 V1 V1 V0 V0 V0 V0 V2 UL 94, 70.degree. C./168 hr CTI (100) V
-- -- -- -- -- -- -- -- -- -- CTI PLC -- -- -- -- -- -- -- -- -- --
Rating
TABLE-US-00006 TABLE 6 Formulation and physical properties of
glass-filled, chlorine- and bromine-free, flame retardant
poly(alkylene ester) compositions (Comparative Example 13 to 19)
Targeted Unit Performance CE13 CE14 CE15 CE16 CE17 CE18 CE19
Component VALOX iQ PBT-1 % 24.58 24.58 24.58 24.58 24.58 24.58
25.08 VALOX iQ PBT-2 % 24.58 24.58 24.58 24.58 24.58 24.58 25.08
Glass Fiber % 30.00 30.00 30.00 30.00 30.00 30.00 30.00 MPP % 5.00
5.00 5.00 5.00 5.00 5.00 5.00 Al-DPA % 12.50 12.50 12.50 12.50
12.50 12.50 11.00 TSAN % 0.50 0.50 0.50 0.50 0.50 0.50 0.50 AO %
0.15 0.15 0.15 0.15 0.15 0.15 0.15 PETS % 0.20 0.20 0.20 0.20 0.20
0.20 0.20 ULTRATALC % 0.50 PEI (ULTEM 1010) % VALOX iQ Elastomer %
1.88 Resin HYTREL % 2.50 1.25 PARALOID EXL % 2.50 1.25 0.63 EEA %
2.50 IGETABOND E % 2.50 LOTADER % 2.50 100 100 100 100 100 100 100
Test Description Flexural Modulus MPa >9800 6460 9600 9250 9370
9190 10600 9860 Flexural Stress at Break MPa >150 110 141 133
148 147 150 155 Izod Impact strength, Un- J/m >470 420 442 371
471 470 447 506 Notched, 23.degree. C. Flame Rating - UL 94, 0.80
mm V0 V0 V0 V0 V0 V1 V0 V0 23.degree. C./48 hr Flame Rating - UL
94, 0.80 mm V0 V0 V0 V0 V1 V1 V0 V2 70.degree. C./168 hr CTI (100)
V -- -- -- -- -- -- -- CTI PLC Rating -- -- -- -- -- -- --
TABLE-US-00007 TABLE 7 Formulation and physical properties of
glass-filled, chlorine- and bromine-free, flame retardant
poly(alkylene ester) compositions (Comparative Example 20 to 25)
Targeted Unit Properties CE20 CE21 CE22 CE23 CE24 CE25 Component
VALOX iQ PBT-1 % 24.83 24.83 25.83 25.58 25.20 25.20 VALOX iQ PBT-2
% 24.83 24.83 25.83 25.58 25.20 25.20 Glass Fiber % 30.00 30.00
30.00 30.00 30.00 30.00 MPP % 5.00 5.00 5.00 5.00 5.00 5.00 Al-DPA
% 12.50 12.50 10.50 10.50 12.50 12.50 TSAN % 0.50 0.50 0.50 0.50
0.50 0.50 AO % 0.15 0.15 0.15 0.15 0.15 0.15 PETS % 0.20 0.20 0.20
0.20 0.20 0.20 ULTRATALC % 0.50 PEI (ULTEM 1010) % VALOX iQ
Elastomer Resin % 1.50 1.50 HYTREL % 2.00 1.25 PARALOID EXL % 2.00
0.50 0.50 1.25 EEA % IGETABOND E % LOTADER % 100 100 100 100 100
100 Test Description Flexural Modulus MPa >9800 9530 9760 10100
10200 8950 10200 Flexural Stress at Break MPa >150 153 156 161
164 143 154 Izod impact strength, J/m >470 531 417 508 561 429
466 Unnotched, 23.degree. C. Flame Rating, UL 94, 0.80 mm V0 V0 V0
V0 V0 V0 V0 23.degree. C./48 hr Flame Rating, UL 94, 0.80 mm V0 V2
V1 V1 V0 V0 V0 70.degree. C./168 hr CTI (100) V -- -- 600 550 -- --
CTI PLC Rating -- -- 0 1 -- --
Discussion
[0115] The results shown in Tables 5, 6, and 7 (Comparative
Examples 3-25) illustrate that use of a single elastomer, or two
elastomers outside of a relatively narrow range did not meet the
minimum targeted performance properties; namely these compositions
did not exhibit the following combination of properties: (a) a
flexural modulus greater than 9800 MPa, (b) a flexural stress
greater than 150 MPa, (c) an unnotched impact strength greater than
470 Joules/meter, and (d) a rating of V0 at a thickness of 0.8 mm,
measured in accordance with the UL 94 protocol. The compositions of
Comparative Examples 1-2 did not meet these properties.
[0116] As shown in Table 5, when impact modifiers including
ELVALOY, IGETABOND, LOTADER, HYTREL, and PARALOID EXL were used
individually at a level of 5 wt %, the 30 wt % glass-filled,
chlorine- and bromine-free poly(alkylene ester) flame retardant
formulations (CE3 to CE7) showed some disadvantages such as in low
flexural modulus, low flexural stress at break, and low unnotched
Izod impact strength. In CE6 and CE7, flame retardance performance
was rated as V1. In CE8 to CE12, where the addition of combinations
of elastomers (HYTREL VALOX iQ Elastomer and PARALOID EXL) at a
level of 5 wt % was used, flexural stress at break was still less
desirable, i.e., less than 150 MPa. In CE12, where 11% Al-DPA was
used, the UL 94 rating at 0.80 mm was V1.
[0117] As shown in Table 6, when impact modifiers including
ELVALOY, IGETABOND, LOTADER, HYTREL and PARALOID EXL were used
individually at a level of 2.5 wt %, the 30% glass-filled,
chlorine- and bromine-free poly(alkylene ester) formulations (CE 13
to CE 17) showed some disadvantages such as in low flexural
modulus, low flexural stress at break, and in some cases, low
un-notched Izod impact strength. In CE16 and CE 17, flame
retardance performance was rated as V1. In CE 18, where the
addition of combinations of elastomers (1.25% HYTREL and 1.25%
PARALOID EXL) at a level of 2.5 wt % was used, flexural stress at
break is still less desirable, i.e., less than 150 MPa. In CE19,
where 11% Al-DPA was used, the UL 94 rating at 0.80 mm was V2.
[0118] As shown in Table 7, when impact modifiers including HYTREL
and PARALOID EXL were used individually at a level of 2.0 wt %, the
30% glass-filled, chlorine- and bromine-free poly(alkylene ester)
formulations (CE20 and CE21) showed some disadvantages such as in
low flexural modulus and failure to meet V0 flame retardance at
0.80 mm. When impact modifiers including HYTREL and PARALOID EXL
were used individually at a level of 1.25 wt %, the 30%
glass-filled, chlorine- and bromine-free poly(alkylene ester) flame
retardant formulations (CE24 and CE25) showed some disadvantages
such as low flexural modulus (CE24) and low unnotched Izod impact
strength, i.e., less than 470 J/m. In CE22 to CE23, containing 2 wt
% of a combination of elastomers (1.50% VALOX iQ Elastomer and 0.5%
PARALOID EXL) and 10.5 wt % of Al-DPA, the formulations showed
either insufficient UL 94 rating (CE22) or less desirable CTI
voltage, i.e., less than 600V (CE23).
[0119] All references cited herein are incorporated by reference in
their entirety. While the invention has been described with
reference to a preferred embodiment, it will be understood by those
skilled in the art that various changes can be made and equivalents
can be substituted for elements thereof without departing from the
scope of the invention. In addition, many modifications can be made
to adapt a particular situation or material to the teachings of the
invention without departing from essential scope thereof Therefore,
it is intended that the invention not be limited to the particular
embodiment disclosed as the best mode contemplated for carrying out
this invention, but that the invention will include all embodiments
falling within the scope of the appended claims.
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